星系的天体物理学

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[1] arXiv:2507.03070 [中文pdf, pdf, html, 其他]

标题： 多数据方法研究开放星团：CCD UBV和Gaia DR3背景下的Roslund 3和Ruprecht 174 显示英文标题

标题： A Multi-Data Approach to Open Clusters: Roslund 3 and Ruprecht 174 in CCD UBV and Gaia DR3 Context

H. Karagoz, T. Yontan, S. Bilir, O. Plevne, T. Ak, S. Ak, R. Canbay, T. Banks

评论： 27页，包括15幅图和9张表，已接受发表于《天文学杂志》

主题： 星系的天体物理学 (astro-ph.GA)

对疏散星团 Roslund 3 和 Ruprecht1 74 的结构、天体物理、运动学和动力学特性进行了详细分析，使用了 CCD UBV 光度测量，并结合了 Gaia DR3 的天体测量和光度数据。通过将 UPMASK 算法应用于 Gaia 自行运动和三角视差，计算了成员概率，从而确定了 Roslund 3 的 198 个可能成员和 Ruprecht 174 的 397 个可能成员。天体物理参数通过经典方法（其中参数是独立确定的）和 MCMC 技术（同时估计它们）进行推导。两种方法的结果之间的一致性证实了它们的可靠性，并突显了经典方法的稳健性。消光值分别为 Roslund 3 的$E(B-V)=0.410\pm 0.046$mag 和 Ruprecht 174 的$E(B-V)=0.615\pm 0.042$mag。估计的距离分别为 Roslund 3 的$d=1687 \pm 121$pc 和 Ruprecht 174 的$d=2385 \pm 163$pc。这两个星团的金属量接近太阳值，Roslund 3 的 [Fe/H] =$0.030 \pm 0.065$dex，Ruprecht 174 的 [Fe/H] =$0.041 \pm 0.064$dex。 对应的年龄分别为$\tau=60\pm 6$和$\tau=520\pm 50$Myr。 目前的质量函数斜率分别为$1.18 \pm 0.13$对于 Roslund 3 和$1.53 \pm 0.30$对于 Ruprecht 174，在不确定范围内与经典的 Salpeter 值一致。 银河系轨道分析表明，这两个星团都是位于太阳圆周内的薄盘成员。 此外，弛豫时间和恒星的空间分布表明，这两个星团已经达到了动力学弛豫，并表现出明显的质量分选迹象。 显示英文摘要

A detailed analysis of the structural, astrophysical, kinematic, and dynamical properties of the open clusters Roslund 3 and Ruprecht1 74 is carried out using CCD UBV photometry in conjunction with astrometric and photometric data from Gaia DR3. Membership probabilities were computed via the UPMASK algorithm applied to Gaia proper motions and trigonometric parallaxes, leading to the identification of 198 likely members for Roslund 3 and 397 for Ruprecht 174. Astrophysical parameters were derived using both the classical approach, where parameters are independently determined, and a MCMC technique, which estimates them simultaneously. The agreement between the results from both methods confirms their reliability and highlights the robustness of the classical method. The reddening values were determined as $E(B-V)=0.410\pm 0.046$ mag for Roslund 3 and $E(B-V)=0.615\pm 0.042$ mag for Ruprecht 174. The estimated distances are $d=1687 \pm 121$ pc for Roslund 3 and $d=2385 \pm 163$ pc for Ruprecht 174. Both clusters exhibit metallicities close to the solar value, with [Fe/H] = $0.030 \pm 0.065$ dex for Roslund 3 and [Fe/H] = $0.041 \pm 0.064$ dex for Ruprecht 174. The corresponding ages were found to be $\tau=60\pm 6$ and $\tau=520\pm 50$ Myr, respectively. The present day mass function slopes were found to be $1.18 \pm 0.13$ for Roslund 3 and $1.53 \pm 0.30$ for Ruprecht 174, consistent with the canonical Salpeter value within uncertainties. Galactic orbital analyses indicate that both clusters are thin-disk members confined within the Solar circle. Additionally, relaxation times and spatial distributions of stars suggest that both clusters have reached dynamical relaxation and exhibit clear signs of mass segregation.

[2] arXiv:2507.03075 [中文pdf, pdf, html, 其他]

标题： 在$z=0.1$-7 时星系恒星种群的年龄 显示英文标题

标题： On the ages of the stellar populations of galaxies at $z=0.1$-7

Eric E. Martínez-García

评论： 已接受发表于MNRAS

主题： 星系的天体物理学 (astro-ph.GA) ; 宇宙学与非星系天体物理学 (astro-ph.CO)

最近的研究报告称，在红移高于$z\sim$2.5 的情况下，星系年龄没有演化，以及星系年龄比宇宙更老。 在本研究中，通过光度法分析了来自 JWST 和 HST 的星系样本，以进一步了解这一天文学现象。 在分析中没有假设任何先验的宇宙学参数，但使用了光谱红移。 与恒星种群合成模型相比，质量加权星系年龄的结果表明，分析对象似乎分为两个子集。 对于大多数对象（60% 假设为平坦-$\Lambda$CDM 宇宙学）的子集，结果表明在红移范围$z$=0.1-7.0 内星系年龄有演化，即更高红移的星系比宇宙更年轻。 讨论了系统误差的来源，并得出结论，红化-年龄-金属量之间的退化，和/或活动星系核发射可能解释了其余 40% 的星系年龄比平坦-$\Lambda$CDM 宇宙学预期的更老。 显示英文摘要

Recent studies have reported a non evolution of galaxy ages at redshifts higher than $z\sim$ 2.5, as well as galaxies older than the Universe. In this work, a sample of galaxies from JWST and HST was analysed via photometry to further understand this astronomical phenomenon. No prior cosmological parameters were assumed in the analysis, but the spectroscopic redshift. When compared to stellar population synthesis models, the results for mass-weighted galaxy ages indicate that the analysed objects seem to be divided into two subsets. The results for the subset with the majority of objects (60\% assuming a flat-$\Lambda$CDM cosmology) indicate an evolution of galaxy ages within the redshift range $z$=0.1-7.0, in the sense that higher redshift galaxies are younger than the Universe. Sources of systematic errors were discussed drawing into conclusion that degeneracies between reddening-age-metallicity, and/or AGN emission may explain the rest 40\% of the galaxies with ages older than expected from a flat-$\Lambda$CDM cosmology.

[3] arXiv:2507.03078 [中文pdf, pdf, html, 其他]

标题： X射线选定的AGN在由巨大Lyman-alpha星云确定的原星系团中的特性 显示英文标题

标题： The properties of X-ray selected AGN in protoclusters pinpointed by Enormous Lya Nebulae

A. Traina, F. Vito, F. Arrigoni-Battaia, C.-C. Chen, C. Vignali, X. Prochaska, S. Cantalupo, A. Pensabene, P. Tozzi, A. Travascio, R. Gilli, M. N. Isla Llave, S. Marchesi, G. Mazzolari

评论： 已接受发表于《天文学与天体物理学》

主题： 星系的天体物理学 (astro-ph.GA) ; 高能天体物理现象 (astro-ph.HE)

原初星系团是宇宙中密度较高的区域，其特征是拥有大量的气体储备。 这种环境使它们成为研究星系-活动星系核共演化的理想实验室，以及超大质量黑洞增长的场所。 生活在这些密集区域的星系预计会有效地增长其超大质量黑洞，从而导致比场域中更高的活动星系核出现率。 一些原初星系团在其核心区显示出延伸的Ly$\alpha$云气，表明存在大量气体储备，但其主要能源机制仍存在争议。 我们的目标是研究三个红移在2.3 < z < 3.2之间的原初星系团中的活动星系核群体及其活动星系核增强现象，这些原初星系团拥有巨大的Ly$\alpha$云气（ELANe）。 此外，我们在Ly$\alpha$云气的相同区域内搜索X射线弥散辐射，以揭示这些原初星系团中的多相气体。 我们使用深度（190-270 ks）的钱德拉观测数据来识别原初星系团成员中的活动星系核，并进行X射线光谱分析以推导这些源的特性。 我们将活动星系核比例和空间密度与在其他已知原初星系团和场域环境中观察到的结果进行比较。 我们在三个原初星系团中发现了11个X射线探测到的活动星系核。 每个结构都包含一个中心、X射线强大的（log$(L_{\rm X}/{\rm erg \, s^{-1}}) \sim 45-46$）类星体，而其他X射线源主要是中等亮度（log$(L_{\rm X}/{\rm erg \, s^{-1}}) \sim 44$）且被遮挡的康普顿薄活动星系核。 我们目标中的活动星系核比例与其他原初星系团的估计值相当，并显著高于低红移星系团中发现的值。 我们还发现，与场域以及原初星系团中非活动星系相比，活动星系核密度有显著增强（2-4 dex）。 最后，我们未从云气中发现显著的软X射线弥散辐射，因此排除了引力加热作为ELANe主要能源机制的可能性。 显示英文摘要

Protoclusters of galaxies are overdense regions of the Universe characterized by large gas reservoirs. Such environments make them perfect laboratories to investigate galaxy-AGN co-evolution and the growth of SMBHs. Galaxies living in such a dense regions are expected to growth efficiently their SMBH, resulting in a higher incidence of AGN than in the field. Some protoclusters exhibit extended Ly$\alpha$ nebulae in their central region, pinpointing the presence of massive gas reservoirs, but whose main powering mechanism is still debated. We aim to investigate the AGN population, and AGN enhancement, in three protoclusters at 2.3 < z < 3.2 which host enormous Ly$\alpha$ nebulae (ELANe). Additionally, we search for the presence of X-ray diffuse emission in the same region of the Ly$\alpha$ nebulae to reveal multi-phase gas in these protoclusters. We use deep (190-270 ks) Chandra observations to identify AGN among the protocluster members and perform X-ray spectral analysis to derive the properties of those sources. We compare the AGN fraction and space density with those observed in other known protoclusters and from the field environment. We find 11 X-ray detected AGN in the three protoclusters. Each structure hosts a central, X-ray powerful (log$(L_{\rm X}/{\rm erg \, s^{-1}}) \sim 45-46$), QSO, while the other X-ray sources are mostly moderately luminous (log$(L_{\rm X}/{\rm erg \, s^{-1}}) \sim 44$) and obscured Compton-Thin AGN. The fraction of AGN in our targets is comparable with estimates for other protoclusters, and significantly higher than what is found for low-redshift clusters. We also find a significant enhancement (2-4 dex) of AGN density with respect to the field and to non active galaxies in the protoclusters. Finally, we find no significant soft X-ray diffuse emissions from the nebulae, thus ruling out gravitational heating as the main powering mechanism of the ELANe.

[4] arXiv:2507.03097 [中文pdf, pdf, html, 其他]

标题： JWST的PEARLS：红移z = 0.94星系中九颗高度放大的恒星温度以及模拟恒星种群对恒星金属量和初始质量函数的依赖性 显示英文标题

标题： JWST's PEARLS: Temperatures of Nine Highly Magnified Stars in a Galaxy at Redshift z = 0.94 and Simulated Stellar Population Dependence on Stellar Metallicity and the Initial Mass Function

Hayley Williams, Patrick L. Kelly, Rogier A. Windhorst, Alexei V. Filippenko, Amruth Alfred, Tom Broadhurst, Wenlei Chen, Christopher J. Conselice, Seth H. Cohen, Jose M. Diego, Benne W. Holwerda, Anton M. Koekemoer, Sung Kei Li, Ashish Kumar Meena, Jose M. Palencia, Massimo Ricotti, Clayton D. Robertson, Bangzheng Sun, S. P. Willner, Haojing Yan, Adi Zitrin

主题： 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

我们展示了对红移z=0.94的单个星系Warhol弧中九颗高度放大的单独恒星的恒星大气建模，该星系被星系团MACSJ0416强烈透镜化。其中七颗瞬变源由Yan等人(2023)识别。这九个源很可能都是温度约为T~4000K的红超巨星。我们提供了用Keck-I和大型双子望远镜获取的Warhol弧的新长缝光谱，并利用这些数据将弧的氧丰度限制为12+log(O/H)=8.45+-0.08。我们使用一系列恒星金属丰度和初始质量函数斜率对合成恒星种群进行了微透镜模拟。模拟可检测恒星的温度分布对恒星金属丰度的选择敏感，将恒星金属丰度设为弧的星际金属丰度（log(Z*/Zsun)=-0.24）会产生与观测一致的模拟温度分布，而较低的恒星金属丰度（log(Z*/Zsun)<-0.75）会产生与观测不一致的模拟温度。对于{\alpha }>1.2，预期检测率与IMF斜率呈强反相关。对于标准IMF斜率alpha=2.35，模拟产生的预期瞬变检测率与哈勃太空望远镜Flashlights滤镜中的观测检测率一致，但在JWST滤镜中预测的检测率高出约3-12倍（<2sigma偏差）。模拟检测率对恒星金属丰度的选择敏感，较低的金属丰度（log(Z*/Zsun)<-0.75）会产生显著较低的模拟检测率，进一步减少与观测的适度偏差。 显示英文摘要

We present stellar atmosphere modeling of JWST NIRCam photometry of nine highly magnified individual stars in a single galaxy at redshift z=0.94 known as the Warhol arc, which is strongly lensed by the galaxy cluster MACSJ0416. Seven of these transients were identified by Yan et al. (2023). The nine sources are all likely red supergiants with temperatures of T~4000K. We present new longslit spectroscopy of the Warhol arc acquired with Keck-I and the Large Binocular Telescope, and use these data to constrain the arc's oxygen abundance to be 12+log(O/H)=8.45+-0.08. We perform a microlensing simulation on synthetic stellar populations using a range of stellar metallicities and initial mass function slopes. The temperature distribution of the simulated detectable stars is sensitive to the choice of stellar metallicity, and setting the stellar metallicity equal to the arc's nebular metallicity (log(Z*/Zsun)=-0.24) produces a simulated temperature distribution that is consistent with the observations, while lower stellar metallicities (log(Z*/Zsun)<-0.75) produce simulated temperatures that are inconsistent with the observations. The expected detection rate is strongly anticorrelated with the IMF slope for {\alpha}>1.2. For the canonical IMF slope alpha=2.35, the simulation yields expected transient detection rates that agree with the observed detection rates in the HST Flashlights filters, but over predicts the detection rate by a factor of ~3-12 (<2sigma tension) in the JWST filters. The simulated detection rate is sensitive to the choice of stellar metallicity, with lower metallicities (log(Z*/Zsun)<-0.75) yielding a significantly lower simulated detection rate that further reduces the modest tension with the observations.

[5] arXiv:2507.03098 [中文pdf, pdf, html, 其他]

标题： JWST的PEARLS：红移0.94透镜星系中的一个候选大质量双星系统 显示英文标题

标题： JWST's PEARLS: A Candidate Massive Binary Star System in a Lensed Galaxy at Redshift 0.94

Hayley Williams, Patrick L. Kelly, Emmanouil Zapartas, Rogier A. Windhorst, Christopher J. Conselice, Seth H. Cohen, Birendra Dhanasingham, Jose M. Diego, Alexei V. Filippenko, Benne W. Holwerda, Terry J. Jones, Anton M. Koekemoer, Ashish Kumar Meena, Massimo Ricotti, Clayton D. Robertson, Payaswini Saikia, Bangzheng Sun, S. P. Willner, Haojing Yan, Adi Zitrin

主题： 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

大质量恒星在宇宙学距离上可以在瞬态微透镜事件中被单独检测到，此时引力透镜放大率可能超过μ ~ 1000。 在JWST NIRCam对一个红移z = 0.94的单个星系“Warhol弧”的成像中发现了九个这样的源，该星系由星系团MACS J0416.1-2403镜像成像。 在此我们报告在相同位置发现的两个同时发生且特征明确的微透镜事件，随后在大约18个月后的一个滤光片中观察到了第三个事件。 这些事件可以解释为由一个红超巨星（T ~ 4000 K）和一个B型（T > 13,000 K）伴星组成的双星系统的微透镜效应。 同时发生的微透镜事件的时间尺度将投影源平面的大小限制为R < 270 AU。 与每个恒星的温度和光度观测约束一致的最可能的双星配置是初始质量M1 = 22.5+7.1-5.5 Msun且初始质量比非常接近于单位的恒星。 一个能够再现所有滤光片中观测到的光变曲线的动力学模型给出了相对较小的横向速度约为50 km/s。 这要求数百km/s的主要速度分量大致平行于微焦散线。 另一种可能性是这三个微透镜事件对应于不相关的恒星穿过不同的微焦散线，但这将意味着在它们共同的位置事件率显著升高，尽管该位置没有潜在的结存在。 显示英文摘要

Massive stars at cosmological distances can be individually detected during transient microlensing events, when gravitational lensing magnifications may exceed mu ~ 1000. Nine such sources were identified in JWST NIRCam imaging of a single galaxy at redshift z = 0.94 known as the "Warhol arc,'' which is mirror-imaged by the galaxy cluster MACS J0416.1-2403. Here we present the discovery of two coincident and well-characterized microlensing events at the same location followed by a third event observed in a single filter approximately 18 months later. The events can be explained by microlensing of a binary star system consisting of a red supergiant (T ~ 4000 K) and a B-type (T > 13,000 K) companion star. The timescale of the coincident microlensing events constrains the projected source-plane size to R < 270 AU. The most likely binary configurations consistent with the observational constraints on the temperatures and luminosities of each star are stars with initial masses M1 = 22.5+7.1-5.5 Msun and an initial mass ratio very close to unity. A kinematic model that reproduces the observed light curve in all filters gives a relatively small transverse velocity of ~50 km/s. This requires the dominant velocity component of several hundreds of km/s to be roughly parallel to the microcaustic. An alternative possibility would be that the three microlensing events correspond to unrelated stars crossing distinct microcaustics, but this would imply a highly elevated rate of events at their common position, even though no underlying knot is present at the location.

[6] arXiv:2507.03118 [中文pdf, pdf, html, 其他]

标题： 测试光度技术测量静止框架紫外光谱斜率与JWST PRISM光谱学的对比 显示英文标题

标题： Testing Photometric Techniques for Measuring the Rest-Frame UV Spectral Slope Against JWST PRISM Spectroscopy

Alexa M. Morales, Steven L. Finkelstein, Pablo Arrabal Haro, Micaela B. Bagley, Antonello Calabrò, Óscar A. Chávez Ortiz, Kelcey Davis, Mark Dickinson, Eric Gawiser, Mauro Giavalisco, Nimish P. Hathi, Michaela Hirschmann, Jeyhan S. Kartaltepe, Anton M. Koekemoer, Arianna S. Long, Ray A. Lucas, Fabio Pacucci, Casey Papovich, Borja Pautasso, Nor Pirzkal, Anthony J. Taylor, Alexander de la Vega, Stephen M. Wilkins, L. Y. Aaron Yung

评论： 12页，3图，提交至ApJ

主题： 星系的天体物理学 (astro-ph.GA)

我们展示了一个样本，包含来自JWST CEERS和RUBIES调查的53个星系光谱，红移z_spec约为5-12，结合了NIRSpec PRISM光谱学与NIRCam测光数据。 我们的目标是利用这些数据来建立在JWST时代的测量紫外光谱斜率（$\beta$）的最佳实践。 我们采用光谱数据中休息框架紫外连续谱的幂律拟合作为我们的基准，或“真实”$\beta$值，并将其与通过三种方法得出的测光估计进行比较：（1）测光幂律拟合，（2）对测光数据拟合的SED模型进行幂律拟合，（3）在Lyman断裂附近的单色拟合，以及（4）在固定休息框架波长处的单色拟合。 我们发现测光幂律拟合最能恢复光谱斜率，偏差和散射最小。 SED拟合表现中等良好，在信号噪声比低的情况下可能变得不可靠时，可以优先选择。 虽然单色估计在过去的研究中被广泛使用，但显示出最大的偏差，在有多个颜色可用时不建议使用。 我们的结果突出了每种方法的局限性和优势，并为在光谱不可用或质量不足时从测光数据中测量$\beta$提供了实用指导。 显示英文摘要

We present a sample of 53 galaxy spectra at z_spec ~ 5-12 from the JWST CEERS and RUBIES surveys, combining NIRSpec PRISM spectroscopy with NIRCam photometry. We aim to use these data to establish best practices for measuring the UV spectral slope ($\beta$) in the era of JWST. We adopt power-law fits to the rest-frame UV continuum from the spectroscopic data as our fiducial, or `true', $\beta$ values, and compare them to photometric estimates derived through three methods: (1) photometric power-law fitting, (2) power-law fitting to an SED model fitted to the photometry, (3) single-color fitting near the Lyman break, and (4) single-color fitting at fixed rest-frame wavelengths. We find that photometric power-law fitting most closely recovers the spectroscopic slopes, with minimal bias and scatter. SED fitting performs moderately well, and can be preferable in cases of low signal-to-noise where photometric power-law fitting may become unreliable. Single-color estimates, while commonly used in past studies, show the most significant deviations and are not recommended when more than a single color is available. Our results highlight the limitations and strengths of each approach and provide practical guidance for measuring $\beta$ from photometry when spectra are unavailable or are of insufficient quality.

[7] arXiv:2507.03124 [中文pdf, pdf, html, 其他]

标题： 最早星系在CANUCS+Technicolor区域的演化：使用完整的NIRCam中等和宽波段滤镜看到的$z\sim10-16$处星系特性 显示英文标题

标题： Earliest Galaxy Evolution in the CANUCS+Technicolor fields: Galaxy Properties at $z\sim10-16$ seen with the Full NIRCam Medium and Broad Band Filters

Yoshihisa Asada, Chris Willott, Adam Muzzin, Maruša Bradač, Gabriel Brammer, Guillaume Desprez, Kartheik Iyer, Danilo Marchesini, Nicholas Martis, Gaël Noirot, Ghassan Sarrouh, Marcin Sawicki, Sunna Withers, Seiji Fujimoto, Giordano Felicioni, Ilias Goovaerts, Jon Judež, Naadiyah Jagga, Maya Merchant, Rosa Mérida, Luke Robbins

评论： 提交至天体物理学杂志；12幅图，4张表，20页；欢迎提出意见

主题： 星系的天体物理学 (astro-ph.GA)

我们通过利用JWST NIRCam成像数据中最丰富的数据之一，呈现了一个$z_{\rm phot}\sim10-16$星系的样本，这些数据来自第一周期的CANUCS调查和第二周期的Technicolor（TEC）调查。 CANUCS+TEC的结合提供了多历元、深度NIRCam图像，在所有中等波段（MBs）和宽波段（BBs）上，覆盖了NIRCam上的22个滤光片，跨越$\sim23\ {\rm arcmin}^2$，涉及三条独立的视线方向。 我们基于光度红移选择高$z$星系候选体，并在$z\sim10-16$处获得了八个候选体，其中包括一个非常可靠的候选体在$z\sim15.4$。 我们样本中的紫外线（UV）光度函数（LF）与之前JWST的研究一致，显示出文献中存在$\sim0.6$dex的散射，标志着在解释$z>10$处星系丰度测量时场间方差的重要性。 我们发现紫外线 LF 在$z>10$处中等程度演化，LF 归一化和光度密度从$z\sim11$到$z\sim15$下降了一个因子$\sim7$，表明比$z<11$更缓的演化。 我们强调 MB 滤镜的重要性，不仅有助于最小化低$z$闯入者的污染，还能最大化完整性。 特别是，当仅基于 BB 数据构建样本时，微弱且不太蓝的星系可能会被遗漏。 BB-only选择样本的污染和不完整性可能在$z>10$时偏倚我们对最早星系演化的看法，包括UV LF偏移$\sim0.6$个数量级，大小-星等关系偏移$\sim0.6$个数量级，以及UV斜率-星等关系偏移$\Delta\beta_{\rm UV}\sim-0.3$。 显示英文摘要

We present a sample of $z_{\rm phot}\sim10-16$ galaxies by exploiting one of the richest JWST NIRCam imaging data, taken in the CANUCS survey in Cycle 1 and the Technicolor (TEC) survey in Cycle 2. The combination of the CANUCS+TEC provides multi-epoch, deep NIRCam images in all medium bands (MBs) and broad bands (BBs) onboard NIRCam (22 filters in total), over $\sim23\ {\rm arcmin}^2$ in three independent lines of sight. We select high-$z$ galaxy candidates based on photometric redshifts, and obtain eight candidates at $z\sim10-16$, including a very robust candidate at $z\sim15.4$. The ultraviolet (UV) luminosity function (LF) from our sample is consistent with previous JWST studies showing a scatter of $\sim0.6$ dex across the literature, marking the significance of the field-to-field variance in interpreting galaxy abundance measurements at $z>10$. We find that the UV LF moderately evolves at $z>10$, and the LF normalization and the luminosity density decline by a factor of $\sim7$ from $z\sim11$ to $z\sim15$, indicating less steep evolution than $z<11$. We highlight the importance of MB filters, not only to minimize the contamination by low-$z$ interlopers but also to maximize the completeness. In particular, faint and less blue galaxies could be missed when the sample is built solely on BB data. The contamination and incompleteness of BB-only selected samples can bias our views of earliest galaxy evolution at $z>10$, including the UV LF by $\sim0.6$ dex, the size-magnitude relation by $\sim0.6$ dex, and the UV slope-magnitude relation by $\Delta\beta_{\rm UV}\sim-0.3$.

[8] arXiv:2507.03127 [中文pdf, pdf, html, 其他]

标题： 水母星系在磁场中的研究：来自数值模拟的见解 显示英文标题

标题： Jellyfish Galaxies in Magnetic Fields: Insights from Numerical Simulations

Jaehyun Lee, Taysun Kimm, Jérémy Blaizot, Julien Devriendt, Sergio Martin-Alvarez, Jinsu Rhee, Maxime Rey, Adrianne Slyz

评论： 28页，25图，已提交至ApJ

主题： 星系的天体物理学 (astro-ph.GA)

水母星系为星系团环境中的激波压力剥离提供了直接证据。 我们使用辐射磁流体动力学模拟，研究磁场在具有多相星际介质（ISM）的水母星系形成中的作用。 我们在富含气体的矮星系上施加磁化（MHD）和非磁化（HD）风，这些星系含有磁化或非磁化星际介质。 由于磁场力对抗局部密度梯度，MHD风比HD风更有效地剥离盘状气体，导致显著不同的激波压力剥离特征。 由MHD风引起的磁场产生强磁场压力，形成了平滑的盘状结构和尾部气体特征。 由于MHD风情况下被剥离的ISM几乎与星系团内介质（ICM）隔离，被剥离的ISM主要在星系盘附近20~kpc范围内形成恒星。 相比之下，非磁化风促进了被剥离的ISM与ICM的高效混合，导致在数百Myr时在远处（$\sim50-100\,$kpc）的尾部形成大量温暖云团，这些云团冷却并坍缩。 因此，远距离尾部的恒星形成仅发生在HD风模拟中。 最后，尽管尾部特征不同，但由于MHD风模拟中气体剥离增加与盘内气体密度增加之间的相互作用，盘内的恒星形成速率仍然相似。 这些结果表明，磁化的ICM可能对水母星系有显著影响，而磁化的ISM则起次要作用。 显示英文摘要

Jellyfish galaxies provide direct evidence of ram pressure stripping in cluster environments. We investigate the role of magnetic fields in the formation of jellyfish galaxies with a multiphase interstellar medium (ISM) using radiation magneto-hydrodynamic simulations. We impose magnetized (MHD) and non-magnetized (HD) winds on the gas-rich dwarf galaxies containing the magnetized or non-magnetized ISM. The MHD winds strip the disk gas more effectively than the HD winds because of the magnetic force acting against the local density gradient, which results in remarkably different ram pressure stripped features. The magnetic fields induced by the MHD winds generate a strong magnetic pressure, which forms smoothed disks and tail gas features. Since the stripped ISM in MHD wind cases travels while being nearly isolated from the intracluster medium (ICM), the stripped ISM mostly forms stars within 20~kpc of the galactic disks. In contrast, non-magnetized winds facilitate the efficient mixing of the stripped ISM with the ICM, resulting in the formation of abundant warm clouds that cool and collapse in the distant ($\sim50-100\,$kpc) tails at times of a few hundred Myr. Consequently, distant tail star formation occurs only in the HD wind runs. Finally, despite the different tail features, the star formation rates in the disk remain similar owing to the interplay between the increased gas stripping and the gas density increase in the disks of the MHD wind runs. These results suggest that the magnetized ICM may have a significant influence on jellyfish galaxies, whereas the magnetized ISM play a minor role.

[9] arXiv:2507.03171 [中文pdf, pdf, html, 其他]

标题： 用宜居世界观测台识别宇宙再电离的贡献者：暗弱星系中的LyC逃逸校准 显示英文标题

标题： Identifying the contributors to cosmic reionization with the Habitable World Observatory: LyC escape calibration in faint galaxies

Annalisa Citro, Cody. A. Carr, Yumi Choi, Sophia. R. Flury, Matthew. J. Hayes, Anne Jaskot, Gagandeep Kaur, Alexandra Le Reste, Matilde Mingozzi, Themiya Nanayakkara, Sally Oey, Claudia. M. Scarlata

评论： 星系增长SCDD，9页，2图。将在收到社区评论后提交给ASP。如果有兴趣支持、提供反馈并作为合著者被包括在内，请使用社区科学案例门户上的表格（https://outerspace.stsci.edu/display/HWOCOMMUNITYSCI/）

主题： 星系的天体物理学 (astro-ph.GA)

研究小尺度物理过程如何塑造大尺度天体物理现象是Astro2020十年调查的关键科学主题之一。 这种相互作用的一个例子是宇宙再电离，其中来自星系的电离光子逃逸到星系际介质（IGM），推动其从中性转变为电离状态在$z>6$。 形成恒星的星系被认为是再电离的主要来源。 然而，一个悬而未决的问题是明亮还是微弱的形成恒星的星系是主要的再电离贡献者。 这取决于逃逸分数$f_{~esc}^{LyC}$——成功逃逸出星系的星际和星系间介质到达IGM的电离光子的比例。 在再电离时期直接测量$f_{~esc}^{LyC}$是不可行的，因为IGM在$z\gtrsim4$时的传输几乎为零。 然而，通过将$f_{~esc}^{LyC}$与低 $z$的间接指标（即与$f_{~esc}^{LyC}$相关的星系特性）进行校准，我们可以估计再电离期间星系中的其值。 目前，$f_{~esc}^{LyC}$ 校准大多局限于 $\sim 90$ 个较亮的 $M_{UV} \sim -18$ 星等，$z\sim 0.3$ 的星等。 然而，最近的模型表明，较暗的星系 ($-19<M_{UV}} <-13$) 可能是再电离的主要贡献者。 我们的科学目标是将 $f_{~esc}^{LyC}$ 校准扩展到如此暗的星等。 借助宜居世界天文台，我们的目标是将统计能力提高 $\sim$ 20 倍。 此外，我们计划达到1/100$L^*$的亮度在$z\sim0.1$。 合适的天体目标将从即将进行的紫外探测器（UVEX）调查中选择。 通过这个科学案例，我们将能够对暗弱星系在宇宙再电离中的作用施加稳健的限制，并确定其主要贡献者。 显示英文摘要

Investigating how small-scale physical processes shape large-scale astrophysical phenomena is one of the key science themes of the Astro2020 decadal Survey. An example of this interplay is Cosmic Reionization, where ionizing photons from galaxies escaped into the intergalactic medium (IGM), driving its transition from neutral to ionized at $z>6$. Star-forming galaxies are thought to be the dominant sources of reionization. However, an open question remains as to whether bright or faint star-forming galaxies are the primary reionization contributors. This depends on the escape fraction $f_{~esc}^{LyC}$ -- the fraction of ionizing photons that successfully escape the galaxy's interstellar and circumgalactic medium to reach the IGM. Performing direct measurements of $f_{~esc}^{LyC}$ during the reionization epoch is not feasible, due to the near-zero transmission of the IGM at $z\gtrsim4$. However, by calibrating $f_{~esc}^{LyC}$ against indirect indicators (i.e. galaxy properties that correlate with $f_{~esc}^{LyC}$) at lower $z$, we can estimate its value in galaxies during reionization. Currently, $f_{~esc}^{LyC}$ calibrations are mostly limited to $\sim 90$ sources brighter $M_{UV} \sim -18$ at $z\sim0.3$. Yet, recent models suggest that fainter galaxies ($-19<M_{UV}<-13$) may be the major contributors to reionization. Our science goal is to extend $f_{~esc}^{LyC}$ calibrations to such faint magnitudes. With the Habitable Worlds Observatory, we aim to achieve a $\sim$ 20-fold increase in statistical power. Additionally, we plan to reach magnitudes as faint as 1/100 $L^*$ at $z\sim0.1$. Suitable targets will be selected from the upcoming Ultraviolet Explorer (UVEX) survey. Through this science case, we will be able to place robust constraints on the role of faint galaxies in the reionization of the Universe and identify its primary contributors.

[10] arXiv:2507.03182 [中文pdf, pdf, html, 其他]

标题： 什么设定了超暗弱矮星的金属量？ 显示英文标题

标题： What Sets the Metallicity of Ultra-Faint Dwarfs?

Vance Wheeler, Andrey Kravtsov, Anirudh Chiti, Harley Katz, Vadim A. Semenov

评论： 14页，7图。将提交至《开放天体物理学杂志》

主题： 星系的天体物理学 (astro-ph.GA)

我们使用来自多个最先进的银河系类似物宇宙学模拟的星际介质（IGM）金属度分布，以及一个超暗矮星系（UFD）形成半解析模型，来模拟MW类似环境中的UFD恒星金属度。 我们研究了不同恒星形成、恒星反馈和第三星族富集处理的模拟，在所有情况下，我们发现只有少数百分比的被UFD前体吸积的IGM被富集到金属度 $\rm [Fe/H]\ge-4$。 当在半解析星系形成模型中使用这些IGM金属度分布设置吸积IGM的金属度时，模型低估了UFD的金属度及其离散度，与观测到的光度-金属度关系相比。 我们的结果表明，IGM富集不是决定UFD恒星金属度的主要机制。相反，UFD恒星金属度主要由内部富集与通过反馈驱动外流导致的金属损失之间的相互作用决定。 我们检查了不同最大外流质量加载因子 $\eta_{\rm max}$的模型，并表明如果最大质量加载因子在 $200\lesssim\eta_{\rm max}\lesssim 2000$的范围内变化，则可以在 $M_V<-7$处再现UFD平均恒星金属度的全部范围。 我们还考虑了不同假设下的IGM富集和 $\eta_{\rm max}$的个体模型星系中的恒星金属度分布函数（MDF）。 我们发现所有考虑的模型与观测到的UFD MDF有合理的吻合，模型差异小于当前金属度测量的不确定性。 显示英文摘要

We use intergalactic medium (IGM) metallicity distributions from several state-of-the-art cosmological simulations of Milky Way analogs and a semi-analytic model of ultra-faint dwarf galaxy (UFD) formation to model the stellar metallicities of UFDs in MW-like environments. We study simulations with different treatments of star formation, stellar feedback, and Population III enrichment, and in all cases, we find that only a few percent of the IGM accretable by UFD progenitors is enriched to metallicities $\rm [Fe/H]\ge-4$. When the metallicity of accreted IGM in the semi-analytic galaxy formation model is set using these IGM metallicity distributions, the model underpredicts UFD metallicities and their scatter compared to the observed luminosity--metallicity relation. Our results indicate that IGM enrichment is not the dominant mechanism setting metallicities of UFD stars. Instead, UFD stellar metallicity is determined primarily by the interplay between internal enrichment and metal loss through feedback-driven outflows. We examine models with different values of the maximum outflow mass loading factor $\eta_{\rm max}$ and show that the full range of average stellar metallicities of UFDs at $M_V<-7$ can be reproduced if the maximum mass loading factor varies in the range $200\lesssim\eta_{\rm max}\lesssim 2000$. We also consider stellar metallicity distribution functions (MDFs) within individual model galaxies with different assumptions about IGM enrichment and $\eta_{\rm max}$. We find that all considered models are in reasonable agreement with observed UFD MDFs, with model differences less than the uncertainties of current metallicity measurements.

[11] arXiv:2507.03218 [中文pdf, pdf, html, 其他]

标题： 早期类型星系中电离气体丝状结构的兴起 显示英文标题

标题： The Rise of Ionized Gas Filaments in Early-Type Galaxies

Ryan Eskenasy, Valeria Olivares, Yuanyuan Su

评论： 21页，9图，提交至《开放天体物理学杂志》的版本

主题： 星系的天体物理学 (astro-ph.GA)

多相丝状星云在冷核星系团中最明亮的星系（BCGs）中普遍存在，为重子物质循环以及超大质量黑洞的供能和反馈提供了关键见解。 然而，BCGs仅占所有早型星系（ETGs）的不到1%。 为了拓宽我们对多相丝状星云如何在ETGs中形成并连接到星系演化整体图景的理解，探索位于星系团或星系群密集中心之外的ETGs至关重要。 我们展示了对126个附近非中心ETGs的VLT-MUSE IFU观测，检测到了其中54个中的温暖电离气体。 这54个中有35个显示旋转盘，其形态和动力学与恒星成分一致，表明其温暖气体可能起源于恒星质量损失。 其余19个则拥有与恒星成分脱耦的丝状星云，类似于在BCGs中观察到的情况。 这些丝状源显示出独特的发射线特性，无法完全通过后渐近巨星分支恒星的光致电离、活动星系核或高速气体冲击来解释。 对于8个已用钱德拉观测的丝状源，其软X射线辐射表明存在热气体。 我们认为它们的发射线可能由热气体冷却产生的极紫外和X射线辐射驱动，类似于冷核星系团，但详细的机制和物理条件可能不同。 作为一个详细的研究案例，我们研究了NGC 4374，这是一个具有广泛钱德拉观测的非中心ETG，并发现其温暖丝状结构的压力高于热丝状结构——这与在冷核星系团中观察到的结果相反。 显示英文摘要

Multiphase filamentary nebulae are ubiquitous in the brightest cluster galaxies (BCGs) of cool-core clusters, providing key insights into the cycle of baryons and the feeding and feedback of supermassive black holes. However, BCGs account for less than 1% of all early-type galaxies (ETGs). To broaden our understanding of how multiphase filamentary nebulae form in ETGs and connect to the greater picture of galaxy evolution, it is crucial to explore ETGs that are outside of the dense centers of galaxy clusters or groups. We present VLT-MUSE IFU observations of 126 nearby non-central ETGs, detecting warm ionized gas in 54 of them. 35 out of 54 display rotating disks that are morphologically and kinematically aligned with their stellar components, suggesting stellar mass loss as the origin of their warm gas. The remaining 19 host filamentary nebulae that are decoupled from the stellar components, resembling those observed in BCGs. These filamentary sources display unique emission line properties that cannot be fully explained by photoionization from post-asymptotic giant branch stars, active galactic nuclei, or fast gas shocks. For the eight filamentary sources that have been observed with Chandra, their soft X-ray emission indicates the presence of hot gas. We posit that their emission lines may be powered by EUV and X-ray radiation from the cooling of the hot gas, similar to cool-core clusters, but the detailed mechanisms and physical conditions may be different. As a detailed study case, we investigate NGC 4374, a non-central ETG with extensive Chandra observations, and find that its warm filaments are over pressured compared to the hot filaments - opposite with what is observed in cool-core clusters.

[12] arXiv:2507.03225 [中文pdf, pdf, html, 其他]

标题： 关于两种冲击代码的对话 显示英文标题

标题： Dialogue Concerning the Two Shock Codes

Yifei Jin, John Raymond

评论： 已接受发表于ApJ

主题： 星系的天体物理学 (astro-ph.GA)

在本文中，我们总结了两种已建立的冲击代码中的冲击物理和辐射传输处理——MAPPINGS代码（Dopita1976,Binette1985,Sutherland1993）和Cox/Raymond代码（以下简称CR代码）（Cox1972,Raymond1976,Raymond1979）。我们比较了冲击速度为50、110、150和300 km/s的冲击模型中的电离状态、温度、电子密度以及能量传输。总之，这两个代码都采用Rankine-Hugoniot流动方程来描述冲击流动，在冲击前沿后的立即区域给出相同的冲击物理特性。这两个代码在辐射传输处理上的不同导致了冲击的电离和热结构以及发射线流量的计算略有不同。这项工作强调了冲击模型中光致电离精细处理的重要性，为冲击代码的未来发展提供了见解，例如3D冲击代码。 显示英文摘要

In this paper, we summarize the shock physics and the treatment of radiative transfer in two well-established shock codes -- the MAPPINGS code (Dopita1976,Binette1985,Sutherland1993) and the Cox/Raymond code (hereafter CR code) (Cox1972,Raymond1976,Raymond1979). We compare the ionization states, temperatures, electron densities, and the energy transportation of the shock models with shock velocities of 50, 110, 150 and 300 km/s. In summary, both codes adopt the Rankine-Hugoniot flow equation to describe the shock flows, giving the same shock physical properties at the immediate area behind shock fronts. The different treatments of radiative transfer in these two codes leads to somewhat different computation of the ionization and thermal structures of shocks, as well as the emission-line fluxes. This work highlights the importance of the delicate treatment of photoionization in shock models, providing insight of the future development of shock codes, such as the 3D shock codes.

[13] arXiv:2507.03228 [中文pdf, pdf, html, 其他]

标题： 鲁宾拥挤场测光：使用数据预览1探索杜鹃座47 显示英文标题

标题： Crowded Field Photometry with Rubin: Exploring 47 Tucanae with Data Preview 1

Tobin M. Wainer, James R. A. Davenport, Eric C. Bellm, Yuankun (David)Wang, Neven Caplar, Elliott S. Burdett, Nora Shipp, John K. Parejko, Gray Thoron, Eric Butler, Maya Salwa, Erin Leigh Howard, Brianna Marie Smart, Wilson Beebe, Ishan F. Ghosh-Coutinho, Bob Abel, Željko Ivezić

评论： 4页，1图，已提交至AAS期刊

主题： 星系的天体物理学 (astro-ph.GA)

我们分析了维拉·C·鲁宾天文台数据预览1的数据，以探讨早期LSST处理管道在47坦帕尼场的表现。 共加-\texttt{对象}目录展示了鲁宾可能实现的深度和精度，恢复了47坦帕尼小麦哲伦星系的清晰颜色-星等图。 不幸的是，现有处理管道无法恢复距离星团中心$\sim$28 pc范围内的源，这是由于源密度极高。 使用鲁宾的强制测光对通过差分成像识别的恒星进行分析，我们可以恢复距离星团中心$\sim$14 pc范围内的源，并利用这个扩展数据集发现了14744个潜在的星团成员。 尽管这种强制测光存在显著的系统误差，但我们的分析展示了鲁宾天文台在拥挤领域详细结构研究方面的潜力。 显示英文摘要

We analyze imaging from Data Preview 1 of the Vera C. Rubin Observatory to explore the performance of early LSST pipelines in the 47 Tucanae field. The coadd-\texttt{object} catalog demonstrates the depth and precision possible with Rubin, recovering well-defined color magnitude diagrams for 47 Tuc Small Magellanic Cloud. Unfortunately, the existing pipelines fail to recover sources within $\sim$28 pc of the cluster center, due to the extreme source density. Using Rubin's forced photometry on stars identified via Difference Imaging, we can recover sources down to $\sim$14 pc from the cluster center, and find 14744 potential cluster members with this extended dataset. While this forced photometry has significant systematics, our analysis showcases the potential for detailed structural studies of crowded fields with the Rubin Observatory.

[14] arXiv:2507.03230 [中文pdf, pdf, html, 其他]

标题： 来自超强自相互作用暗物质的小红点 显示英文标题

标题： Little Red Dots from Ultra-Strongly Self-Interacting Dark Matter

M. Grant Roberts, Lila Braff, Aarna Garg, Stefano Profumo, Tesla Jeltema

评论： 16页，2图

主题： 星系的天体物理学 (astro-ph.GA)

我们研究最近发现的高红移、被遮挡类星体群体——称为“小红点”（LRDs）——是否源自由超强自相互作用暗物质（uSIDM）驱动的早期黑洞种子形成的可能性。 在此框架中，由于大的自相互作用截面，暗物质晕发生重力热核心坍缩，导致在红移 $z \gtrsim 5$时快速形成质量为 $\gtrsim 10^{5} M_\odot$ 的大质量黑洞（BH）种子。 我们开发了一个半解析模型，追踪暗物质晕种群的演化、坍缩红移 $z_{\rm coll}$ 以及相应的黑洞质量函数。 黑洞增长通过对数正态分布的爱丁顿比率和有限占空比进行随机建模。 我们发现，uSIDM情景自然地再现了LRDs的关键观测特性，包括它们的丰度、紧凑性和特征黑洞质量，同时提供了一种难以在标准CDM模型中实现的早期遮挡黑洞形成机制。 预测的 $z \sim 5$ 处的超大质量黑洞质量函数与LRD观测数据和SIDM合并树模拟表现出良好的一致性，特别是在高质端 $(m_{\rm BH} \gtrsim 10^{7} M_\odot)$。 这些结果表明，LRDs可能作为探索奇异暗物质领域的强大观测示踪物，而早期宇宙中的超大质量黑洞形成可能显著受到非引力暗物质相互作用的影响。 显示英文摘要

We investigate the possibility that the recently identified population of high-redshift, obscured quasars - known as "Little Red Dots" (LRDs) - originates from early black hole seed formation driven by ultra-strongly self-interacting dark matter (uSIDM). In this framework, dark matter halos undergo gravothermal core collapse due to large self-interaction cross sections, resulting in the rapid formation of massive black hole (BH) seeds with masses $\gtrsim 10^{5} M_\odot$ at redshifts $z \gtrsim 5$. We develop a semi-analytic model that tracks the evolution of the dark matter halo population, the redshift of collapse $z_{\rm coll}$, and the corresponding BH mass function. Black hole growth is modeled stochastically via a log-normal Eddington ratio distribution and a finite duty cycle. We find that the uSIDM scenario naturally reproduces key observed properties of LRDs, including their abundance, compactness, and characteristic BH masses, while offering a mechanism for early, obscured black hole formation that is difficult to achieve in standard CDM-based models. The predicted SMBH mass function at $z \sim 5$ shows excellent agreement with LRD observational data and SIDM merger-tree simulations, particularly at the high-mass end $(m_{\rm BH} \gtrsim 10^{7} M_\odot)$. These results suggest that LRDs may serve as powerful observational tracers of exotic dark sector physics and that SMBH formation in the early universe could be significantly shaped by non-gravitational dark matter interactions.

[15] arXiv:2507.03260 [中文pdf, pdf, html, 其他]

标题： 基于神经网络的DESI类星体测光红移预测 显示英文标题

标题： Photometric Redshift Predictions with a Neural Network for DESI Quasars

Jeremy P. Moss, Stephen J. Curran, Yvette C. Perrott

评论： 24页，20图，12表

主题： 星系的天体物理学 (astro-ph.GA)

精确的红移测量对于研究类星体（QSOs）的演化及其在宇宙结构形成中的作用至关重要。虽然光谱红移提供了高精度，但对于大规模调查中检测到的大量源来说，这并不实际。通过宽带通量得出的光度红移提供了一种高效的替代方法，尤其是在结合机器学习技术时。在本工作中，我们开发并评估了一个神经网络模型，用于预测暗能量光谱巡天仪器（DESI）早期数据发布光谱目录中类星体的红移，使用来自DESI、广域红外线巡天探测器（WISE）和银河系演化探测器（GALEX）的光度数据。我们比较了神经网络模型与k-最近邻方法的性能，这两种方法是在此研究中测试的最准确且资源消耗最少的方法，优化模型参数并使用标准统计指标评估准确性。我们的结果表明，结合GALEX的紫外光度数据可以提高光度红移估计，相比仅使用近红外和光学波段训练的模型，减少了散射和灾难性异常值。神经网络与光谱红移的相关系数为$0.9187$，归一化中位数绝对偏差为$0.197$，这比其他方法有显著改进。我们的工作结合了DESI、WISE和GALEX的测量数据，提供了稳健的预测，解决了在大红移范围内预测类星体光度红移的困难。 显示英文摘要

Accurate redshift measurements are essential for studying the evolution of quasi-stellar objects (QSOs) and their role in cosmic structure formation. While spectroscopic redshifts provide high precision, they are impractical for the vast number of sources detected in large-scale surveys. Photometric redshifts, derived from broadband fluxes, offer an efficient alternative, particularly when combined with machine learning techniques. In this work, we develop and evaluate a neural network model for predicting the redshifts of QSOs in the Dark Energy Spectroscopic Instrument (DESI) Early Data Release spectroscopic catalogue, using photometry from DESI, the Widefield Infrared Survey Explorer (WISE) and the Galactic Evolution Explorer (GALEX). We compare the performance of the neural network model against a k-Nearest Neighbours approach, these being the most accurate and least resource-intensive of the methods trialled herein, optimising model parameters and assessing accuracy with standard statistical metrics. Our results show that incorporating ultraviolet photometry from GALEX improves photometric redshift estimates, reducing scatter and catastrophic outliers compared to models trained only on near infrared and optical bands. The neural network achieves a correlation coefficient with spectroscopic redshift of $0.9187$ with normalised median absolute deviation of $0.197$, representing a significant improvement over other methods. Our work combines DESI, WISE and GALEX measurements, providing robust predictions which address the difficulties in predicting photometric redshift of QSOs over a large redshift range.

[16] arXiv:2507.03324 [中文pdf, pdf, html, 其他]

标题： 无线电宁静开启变化观察活动星系核的物理机制 显示英文标题

标题： The physical mechanism of radio-quiet turn-on changing-look active galactic nuclei

Shuang-Liang Li, Xinwu Cao

评论： 7页，2图，已接受发表于ApJ

主题： 星系的天体物理学 (astro-ph.GA) ; 高能天体物理现象 (astro-ph.HE)

建议吸积盘中的质量吸积率的变化可能是大多数变化外观活动星系核（CL AGNs）出现的原因。 然而，薄盘的粘滞时间尺度远长于观测到的CL AGNs的时间尺度。 尽管通过引入大尺度磁场可以解决这个问题，但缺乏/弱大尺度磁场的无线电安静CL AGNs的机制仍然是一个谜。 在本工作中，我们假设薄吸积盘是从内部的流动主导吸积流（ADAF）坍缩而来，而不是通过流动被外部薄盘取代。 这一想法通过将ADAF的冷却时间尺度（$t_{\rm cool}$）与开启型CL AGNs的观测时间尺度（$t_{\rm tran}$）进行比较来验证。 我们从归档数据中整理了一个包含102个开启型CL AGNs的样本，并基于一些常规假设，利用临界质量吸积率计算了ADAF的冷却时间尺度。 结果发现，在大多数CL AGNs中，$t_{\rm cool}$远小于$t_{\rm tran}$，这验证了我们的假设，尽管$t_{\rm cool}$与$t_{\rm tran}$（$t_{\rm cool}<t_{\rm tran}$）不一致。 然而，这是合理的，因为大多数CL AGNs仅被观测了两次，表明观测的时间尺度$t_{\rm tran}$是最大值，因为变化-看可以确实在第二次观测之前发生。 显示英文摘要

It is suggested that the variation of mass accretion rate in accretion disk may be responsible for the occurrence of most changing-look active galactic nuclei (CL AGNs). However, the viscous timescale of a thin disk is far longer than the observed timescale of CL AGNs. Though this problem can be resolved by introducing the large-scale magnetic field, the mechanism for radio-quiet CL AGNs with weak/absent large-scale magnetic field remains a mystery. In this work, we assume that the thin accretion disk is collapsed from the inner advection-dominated accretion flow (ADAF) instead of substituting by the outer thin disk through advection. This idea is tested by comparing the cooling timescale ($t_{\rm cool}$) of an ADAF with the observed timescale ($t_{\rm tran}$) of turn-on CL AGNs. We compile a sample of 102 turn-on CL AGNs from the archived data and calculate the cooling timescale of an ADAF with the critical mass accretion rate based on some conventional assumptions. It is found that $t_{\rm cool}$ is much shorter than $t_{\rm tran}$ in most of the CL AGNs, which validates our assumption though $t_{\rm cool}$ is not consistent with $t_{\rm tran}$ ($t_{\rm cool}<t_{\rm tran}$). However, this is reasonable since most of the CL AGNs were observed only two times, indicating that the observed timescale $t_{\rm tran}$ is the maximum value because the changing-look can indeed happen before the second observation.

[17] arXiv:2507.03420 [中文pdf, pdf, html, 其他]

标题： FEAST：使用JWST/NIRCam探测星暴矮星系NGC4449的恒星种群 显示英文标题

标题： FEAST: probing the stellar population of the starburst dwarf galaxy NGC4449 with JWST/NIRCam

Matteo Correnti, Giacomo Bortolini, Flavia Dell'Agli, Angela Adamo, Michele Cignoni, Elena Sacchi, Monica Tosi, Alex Pedrini, Anne S. M. Buckner, Daniela Calzetti, Ana Duarte-Cabral, Bruce G. Elmegreen, Helena Faustino Vieira, John S. Gallagher, Kathryn Grasha, Benjamin Gregg, Kelsey E. Johnson, Thomas S.-Y. Lai, Drew Lapeer, Sean T. Linden, Matteo Messa, Goran Ostlin, Elena Sabbi, Linda J. Smith, Paolo Ventura

评论： 《天体物理学杂志》待发表，21页，14图，1表

主题： 星系的天体物理学 (astro-ph.GA)

我们展示了星暴不规则星系NGC 4449的新JWST/NIRCam观测结果，这些观测是在第一周期内作为Feedback in Emerging extrAgalactic Star clusTers (FEAST)项目的一部分获得的，我们利用这些观测来研究其分辨的恒星种群及其空间分布。 NGC4449 NIR颜色-星等图揭示了广泛的恒星种群，涵盖了不同的演化阶段，从年轻的主序星，到古老的红巨星分支恒星和渐近巨星分支（AGB）恒星。 对其空间分布的分析显示，较年轻的（< 10 Myr）种群形成了与星系南北轴对齐的S形分布，而年龄为10 - 60 Myr的恒星显示出从北向南的集中变化，这与外部相互作用或潮汐效应可能触发了空间上不同的爆发性恒星形成的可能性一致。 年龄相近的团块通常遵循这些分布，表明在每个星系区域中，团块和场星以相同的速度形成。 得益于JWST数据前所未有的高空间分辨率和灵敏度，我们恢复了富氧AGB种群和碳星分支之间的清晰间隙以及一个大质量AGB恒星“手指”的存在。 对这些恒星的分析可以为AGB演化模型和该星系中的尘埃生产提供约束。 这些结果确认了NGC 4449作为本地矮星暴星系的显著例子，正在进行复杂且可能由外部驱动的恒星形成，并强调了JWST在探测附近星暴系统中恒星完整生命周期方面的强大能力。 显示英文摘要

We present new JWST/NIRCam observations of the starburst irregular galaxy NGC 4449, obtained in Cycle 1 as part of the Feedback in Emerging extrAgalactic Star clusTers (FEAST) program, which we use to investigate its resolved stellar populations and their spatial distributions. NGC4449 NIR color-magnitude diagrams reveal a broad range of stellar populations, spanning different evolutionary phases, from young main sequence stars, to old red giant branch stars and asymptotic giant branch (AGB) stars. The analysis of their spatial distributions shows that younger (< 10 Myr) populations form an S-shaped distribution aligned with the galaxy's north-south axis, while stars aged 10 - 60 Myr show shifting concentrations from the north to the south, consistent with the possibility that external interactions or tidal effects may have triggered star formation in spatially distinct bursts. Clusters of comparable ages generally follow these distributions, suggesting that cluster and field stars form at the same pace in each galaxy region. Thanks to the unprecedented high-spatial resolution and sensitivity of the JWST data we recover a clear gap between Oxygen-rich and the carbon star branch of the AGB population and the presence of a massive AGB star "finger". The analysis of these stars can provide constraints on AGB evolution models and dust production in this galaxy. These results confirms NGC 4449 status as a compelling example of a local dwarf starburst galaxy undergoing complex and possibly external driven star formation and underscore the power of JWST in probing the full lifecycle of stars in nearby starburst systems.

[18] arXiv:2507.03663 [中文pdf, pdf, html, 其他]

标题： LMC引起的银河晕扰动：I. 晕舞模拟套件和观测预测 显示英文标题

标题： LMC-induced Perturbations in the Milky Way Halo:I. HaloDance Simulation Suite and Observational Forecasts

Yanjun Sheng, Yuan-Sen Ting, Xiang-Xiang Xue

评论： 22页，17图，提交至MNRAS

主题： 星系的天体物理学 (astro-ph.GA)

银河系（MW）与大麦哲伦星云（LMC）之间的引力相互作用扰动了MW晕的密度和运动学，编码了两个星系质量和结构的信息。我们提出了一套2,848个高分辨率（$10^7$颗粒）的N体模拟，系统地变化两个星系晕的质量和形状。我们模拟了晕星（30--120 kpc）的平均速度和速度弥散度如何依赖于系统参数，并预测了当前和未来观测可达到的约束。假设盖亚DR3级别的天体测量数据，20 km/s的径向速度精度，10%的距离精度，并且有一个$\sim$4,000颗RR造父变星的样本，我们实现了MW质量的$\sigma$不确定性为$0.11 \times 10^{12} M_\odot$，LMC质量的$2.33 \times 10^{10} M_\odot$不确定性，晕浓度（$c$）为2.38，以及晕扁率（$q$）为0.06。这些分别对应于相对于基准值的11%、16%、25%和6%的分数不确定性。改进的盖亚自行（DR5）带来适度的提升（最多14%），而增加径向速度相对于仅使用盖亚天体测量数据可将约束提高多达60%。 将样本量加倍至$\sim$8,000 颗恒星可带来额外 30% 的改进，而减少距离不确定性影响很小 ($\le$10%)。 平均速度追踪 LMC 引起的扰动，而速度弥散度限制 MW 暗物质晕特性，共同打破退化性。 我们的结果表明，结合 Gaia 天体测量数据与大规模光谱巡天将能够精确表征 MW-LMC 系统。 这篇方法学论文建立了解释观测结果的框架；未来的工作将把这些工具应用于现有的光谱数据集。 完整的模拟套件 HaloDance 将在以下网址公开提供：https://github.com/Yanjun-Sheng/HaloDance. 显示英文摘要

The gravitational interaction between the Milky Way (MW) and the Large Magellanic Cloud (LMC) perturbs the MW halo's density and kinematics, encoding information about both galaxies' masses and structures. We present a suite of 2,848 high-resolution ($10^7$ particles) N-body simulations that systematically vary the mass and shape of both galaxies' haloes. We model how the mean velocities and velocity dispersions of halo stars (30--120 kpc) depend on system parameters, and forecast constraints achievable with current and future observations. Assuming Gaia DR3-level astrometry, 20 km/s radial velocity precision, 10% distance precision, and a sample of $\sim$4,000 RR Lyrae stars, we achieve 1$\sigma$ uncertainties of $0.11 \times 10^{12} M_\odot$ in MW mass, $2.33 \times 10^{10} M_\odot$ in LMC mass, 2.38 in halo concentration ($c$), and 0.06 in halo flattening ($q$). These correspond to fractional uncertainties of 11%, 16%, 25%, and 6% respectively, relative to fiducial values. Improved Gaia proper motions (DR5) yield modest gains (up to 14%), while adding radial velocities improves constraints by up to 60% relative to using Gaia astrometry alone. Doubling the sample size to $\sim$8,000 stars yields an additional 30% improvement, whereas reducing distance uncertainties has minimal impact ($\le$10%). Mean velocities trace LMC-induced perturbations, while velocity dispersions constrain MW halo properties, jointly breaking degeneracies. Our results demonstrate that combining Gaia astrometry with large spectroscopic surveys will enable precise characterization of the MW-LMC system. This methodology paper establishes the framework for interpreting observations; future work will apply these tools to existing spectroscopic datasets. The full simulation suite, HaloDance, will be made publicly available at: https://github.com/Yanjun-Sheng/HaloDance.

[19] arXiv:2507.03679 [中文pdf, pdf, html, 其他]

标题： JWST 预期在猎户座星云团中的棕矮星候选体光谱 显示英文标题

标题： JWST Spectra of Brown Dwarf Candidates in the Orion Nebula Cluster

K. L. Luhman

评论： MNRAS快报，待发表

主题： 星系的天体物理学 (astro-ph.GA) ; 地球与行星天体物理学 (astro-ph.EP)

我分析了200个朝向猎户座星云团（ONC）的天体的档案光谱，这些光谱是由詹姆斯·韦布空间望远镜（JWST）上的近红外光谱仪（NIRSpec）获得的。 我利用这些数据来评估星团成员身份并测量目标的光谱类型。 53个天体被归类为可能的星团成员，其中24个的光谱类型表明可能是棕矮星（$>$M6）。 NIRSpec的目标中有7个之前被识别为“木星质量双星天体”（JuMBOs），但根据NIRSpec的数据，它们都是背景天体而非棕矮星。 这些天体的光谱分类与我最近对ONC中JWST测光的研究结果一致，该研究发现只有少数JuMBO组分具有棕矮星预期的颜色，其中没有一个形成具有独特宽分离度或相对于已知棕矮星双星而言低质量的双星。 显示英文摘要

I present an analysis of archival spectra of 200 sources toward the Orion Nebula Cluster (ONC) that were obtained with the Near-Infrared Spectrograph (NIRSpec) on board the James Webb Space Telescope (JWST). I have used these data to assess cluster membership and measure spectral types for the targets. Fifty-three sources are classified as likely cluster members, 24 of which have spectral types that are suggestive of brown dwarfs ($>$M6). Seven of the NIRSpec targets were previously identified as "Jupiter-mass binary objects" (JuMBOs), all of which are background sources rather than brown dwarfs based on the NIRSpec data. The spectral classifications of those objects are consistent with the results of my recent study of the JWST photometry in the ONC, which found that only a few JuMBO components have the colors expected for brown dwarfs, none of which form pairs that have uniquely wide separations or low masses relative to known binary brown dwarfs.

[20] arXiv:2507.03685 [中文pdf, pdf, html, 其他]

标题： 晚中新世$^{10}$钛异常和超新星的可能性 显示英文标题

标题： The late Miocene $^{10}$Be anomaly and the possibility of a supernova

E. Maconi, J. Alves, J. Großschedl, A. Rottensteiner, C. Swiggum, S. Ratzenböck

主题： 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

最近对来自太平洋中部和北部深海铁锰结壳中宇宙成因的$^{10}$Be 的测量显示，在1150万至900万年前之间出现了一个异常浓度，峰值出现在1010万年前。 一种可能的解释是附近发生了超新星（SN）事件。 鉴于此以及太阳系在该时期接近猎户座恒星形成区的邻近性，我们估计在异常开始到峰值期间至少发生一次SN的概率。 利用基于盖亚DR3的开放星团目录，我们回溯了2725个星团和太阳在过去2000万年内的轨道，并计算了预期的SN事件数量。 我们发现有19个星团在1150万至1010万年前的时间间隔内，以超过1%的概率在距离太阳100秒差距范围内产生至少一次SN。 从太阳开始，总累积概率在35秒差距处超过零，并随着距离增加迅速上升，在100秒差距附近达到68%。 有两个年轻的星团主导了SN的概率：ASCC 20在70秒差距以内贡献最大，而OCSN 61在更远的距离上变得更加重要。 我们的结果支持了$^{10}$Be 异常起源于SN的可能性，并强调了从独立的陆地档案中获取额外的$^{10}$Be 记录的重要性，以确定该异常是天体物理起源还是地球起源。 显示英文摘要

Recent measurements of cosmogenic $^{10}$Be in deep-ocean ferromanganese crusts from the Central and Northern Pacific have revealed an anomalous concentration between 11.5 and 9.0 Myr ago, peaking at 10.1 Myr. One possible explanation is a nearby supernova (SN) event. Motivated by this and by the proximity of the Solar System to the Orion star-forming region during that period, we estimate the probability that at least one SN occurred between the onset and peak of the anomaly. Using an open cluster catalog based on Gaia DR3, we trace back the orbits of 2725 clusters and the Sun over the past 20 Myr and compute the expected number of SN events. We find 19 clusters with a probability greater than 1% each of producing at least one SN within 100 pc of the Sun in the time interval 11.5-10.1 Myr ago. The total cumulative probability exceeds zero at 35 pc from the Sun and increases rapidly with distance, reaching 68% near 100 pc. Two young clusters dominate the SN probability: ASCC 20 contributes most within 70 pc, while OCSN 61 becomes more significant beyond that distance. Our results support the plausibility of a SN origin for the $^{10}$Be anomaly and highlight the importance of additional $^{10}$Be records from independent terrestrial archives to determine whether the anomaly is of astrophysical or terrestrial origin.

[21] arXiv:2507.03742 [中文pdf, pdf, html, 其他]

标题： 深度势能：使用归一化流在GDR3中恢复太阳邻域的引力势和局部模式速度 显示英文标题

标题： Deep Potential: Recovering the gravitational potential and local pattern speed in the solar neighborhood with GDR3 using normalizing flows

Taavet Kalda, Gregory M. Green

评论： 24页，13图

主题： 星系的天体物理学 (astro-ph.GA)

银河系的引力势包含了关于整个星系中所有物质（包括暗物质）分布的信息。 盖亚数据发布3揭示了一个复杂的结构，这需要灵活的银河系引力势模型。 我们利用560万颗主序星的样本，在太阳周围1千秒差距的范围内，使用一种称为“深度势能”的数据驱动方法来绘制完整的三维引力势。 这种方法对银河系的动力学做出了最少的假设——即恒星是一个在旋转参考系中统计上稳定的无碰撞系统（模式速度待确定）。 我们使用归一化流来建模6维相空间中的恒星分布，使用神经网络来建模引力网络。 我们恢复了本地模式速度为$\Omega_p = 28.2\pm0.1\mathrm{\,km/s/kpc}$，本地总物质密度为$\rho=0.086\pm0.010\mathrm{\,M_\odot/pc^3}$以及本地暗物质密度为$\rho_\mathrm{DM}=0.007\pm0.011\mathrm{\,M_\odot/pc^3}$。 完整的三维模型表现出空间波动，这可能源于模型架构和银河系的非平稳性。 显示英文摘要

The gravitational potential of the Milky Way encodes information about the distribution of all matter -- including dark matter -- throughout the Galaxy. Gaia data release 3 has revealed a complex structure that necessitates flexible models of the Galactic gravitational potential. We make use of a sample of 5.6 million upper-main-sequence stars to map the full 3D gravitational potential in a one-kiloparsec radius from the Sun using a data-driven approach called ``Deep Potential''. This method makes minimal assumptions about the dynamics of the Galaxy -- that the stars are a collisionless system that is statistically stationary in a rotating frame (with pattern speed to be determined). We model the distribution of stars in 6D phase space using a normalizing flow and the gravitational network using a neural network. We recover a local pattern speed of $\Omega_p = 28.2\pm0.1\mathrm{\,km/s/kpc}$, a local total matter density of $\rho=0.086\pm0.010\mathrm{\,M_\odot/pc^3}$ and local dark matter density of $\rho_\mathrm{DM}=0.007\pm0.011\mathrm{\,M_\odot/pc^3}$. The full 3D model exhibits spatial fluctuations, which may stem from the model architecture and non-stationarity in the Milky Way.

[22] arXiv:2507.03744 [中文pdf, pdf, html, 其他]

标题： 评估分子气体的分层动态状态：NGC 253中3到300 pc范围内的维里参数 显示英文标题

标题： Assessing the hierarchical dynamical state of molecular gas: virial parameters from 3 to 300 pc in NGC 253

Elias K. Oakes, Christopher M. Faesi, Erik Rosolowsky, Adam K. Leroy, Simon C. O. Glover, Annie Hughes, Sharon E. Meidt, Eva Schinnerer, Jiayi Sun, Amirnezam Amiri, Ashley T. Barnes, Zein Bazzi, Ivana Bešlić, Guillermo A. Blanc, Charlie Burton, Ryan Chown, Enrico Congiu, Daniel A. Dale, Simthembile Dlamini, Hao He, Eric W. Koch, Fu-Heng Liang, Miguel Querejeta, Sumit K. Sarbadhicary, Sophia K. Stuber, Antonio Usero, Thomas G. Williams

评论： 31页，16图，已提交至天体物理学杂志

主题： 星系的天体物理学 (astro-ph.GA)

了解星际介质（ISM）的动力学状态在空间尺度上的变化，可以为气体的组织方式以及最终坍缩形成恒星提供重要的见解。 为此，我们展示了ALMA $^{12}\mathrm{CO}(2-1)$ 在 $7$ pc（$0.4''$）的空间分辨率下对位于附近（$D = 3.5$ Mpc）的巨质量、恒星形成星系NGC 253盘内的 $1.4~\mathrm{kpc}\times5.6~\mathrm{kpc}$ （$1'.3\times1'.3$）区域的观测结果。 我们使用分层多尺度树状图算法对这种发射进行分解，以识别2463个结构，其解卷积大小范围从$\sim3$到$300$pc，完整到限制质量$10^4~\mathrm{M_\odot}$。 通过将这些结构的维里参数与包括大小、质量、表面密度、速度弥散和层次位置在内的物理特性进行比较，我们进行了全面搜索，以寻找引力束缚结构出现的优选尺度。 最终，我们在数据中没有识别出任何束缚天体的涌现尺度，也没有发现维里参数与结构大小之间的相关性。 这些发现表明，不能使用引力束缚来定义分子云，并强调了需要多尺度方法来表征星际介质。 显示英文摘要

Understanding how the dynamical state of the interstellar medium (ISM) changes across spatial scales can provide important insights into how the gas is organized and ultimately collapses to form stars. To this end, we present ALMA $^{12}\mathrm{CO}(2-1)$ observations at $7$ pc ($0.4''$) spatial resolution across a $1.4~\mathrm{kpc}\times5.6~\mathrm{kpc}$ ($1'.3\times1'.3$) region located in the disk of the nearby ($D = 3.5$ Mpc), massive, star-forming galaxy NGC 253. We decompose this emission with a hierarchical, multiscale dendrogram algorithm to identify 2463 structures with deconvolved sizes ranging from $\sim3$ to $300$ pc, complete to a limiting mass of $10^4~\mathrm{M_\odot}$. By comparing the virial parameter of these structures against physical properties including size, mass, surface density, velocity dispersion, and hierarchical position, we carry out a comprehensive search for a preferred scale at which gravitationally bound structures emerge. Ultimately, we do not identify any emergent scale for bound objects in our data, nor do we find a correlation between the virial parameter and structure sizes. These findings suggest that gravitational binding cannot be used to define molecular clouds and emphasize the need for multiscale approaches to characterize the ISM.

[23] arXiv:2507.03750 [中文pdf, pdf, html, 其他]

标题： 利用宜居世界观测站绘制星系风和星系晕介质的小尺度结构 显示英文标题

标题： Mapping Galactic Winds and Small-scale Structure in the Circumgalactic Medium with Habitable Worlds Observatory

Joseph N. Burchett, Deborah M. Lokhorst, Yakov Faerman, Kevin France, Kate H. R. Rubin, David S. N. Rupke, Sanchayeeta Borthakur

评论： 科学案例开发文件，来自宜居世界天文台CGM/IGM工作组。材料已通过同行评审并被接受发表在《JATIS》上。可通过https://tinyurl.com/3vmemez9表单提供支持和评论。

主题： 星系的天体物理学 (astro-ph.GA)

我们提出一个科学案例，旨在利用宜居世界天文台（HWO）通过瞄准紫外线发射线来在发射中绘制星系际介质（CGM）的图像，这些发射线追踪了10^4 - 10^6 K的气体，这些气体参与了驱动星系演化的反馈和吸积机制。 尽管通过吸收线实验以及地面上光学和射电发射的有限工作，CGM-星系连接关系显然可见，但关于这些宇宙生态系统如何交换物质和能量的连接性质仍知之甚少。 我们概述了利用宜居世界天文台（HWO）进行的两项实验，分别采用多目标光谱学来绘制千秒差距尺度的CGM结构，如星系超级风，以及积分场光谱学来揭示亚千秒差距尺度的过程，如热不稳定性，这些过程被理论认为控制着长期在铅笔束吸收调查中检测到的冷气体储层。 本文是对HWO的CGM/IGM工作组制定的科学案例文件的改编。 显示英文摘要

We present a science case for the Habitable Worlds Observatory (HWO) to map the circumgalactic medium (CGM) in emission by targeting ultraviolet emission lines, which trace the 10^4 - 10^6 K gas engaged in the feedback and accretion mechanisms driving galaxy evolution. While the CGM-galaxy connection is clearly evident through absorption line experiments and limited work done in optical and radio emission from the ground, the nature of this connection is poorly understood with regard to how these cosmic ecosystems exchange matter and energy. We outline a two-pronged experiment with Habitable Worlds Observatory (HWO) utilizing both multi-object spectroscopy to map kpc-scale CGM structures such as galactic superwinds and integral field spectroscopy to unveil the sub-kpc-scale processes such as thermal instabilities, which are theorized to govern the cool gas reservoirs long detected in pencil-beam absorption surveys. This article is an adaptation of a science case document developed by HWO's CGM/IGM Working Group.

[24] arXiv:2507.03788 [中文pdf, pdf, html, 其他]

标题： 潮汐力在分子云动力学中的重要性 显示英文标题

标题： The Importance of Tidal Forces in Molecular Cloud Dynamics

JinWoo Lee, Alexa Saur, Mordecai-Mark Mac Low, Hui Li

评论： 被天体物理杂志接受。前两位作者贡献相同

主题： 星系的天体物理学 (astro-ph.GA)

我们通过检查由经典维里参数诊断的明显束缚性如何与受环境潮汐力影响的云的实际引力状态相关，来研究潮汐力在分子云形成中的作用。 云是在来自银河系质量星系模拟的缩放区域中通过分形算法识别的，该模拟使用Voronoi网格代码AREPO，在亚秒差距分辨率下解析恒星形成区域。 为了观察不同的环境，我们使用了三个不同区域的数据，这些区域在中心、相当于太阳圆环附近以及模拟星系的外围演化不同，并且在三个不同的时间点，每个时间点相隔2 Myr。 我们计算了潮汐力对所有识别出的云的重要性。 然后我们将仅包括其内部势能的云的束缚性与同时包括外部引力势能的束缚性进行比较。 这种比较表明，潮汐力可以使看似束缚的云解束缚，并使看似非束缚的云束缚。 我们通过将云的维里参数与其表面密度进行比较，确定潮汐张量的最大和最小特征值的比值，并确定每个被检查区域中引力不稳定的强度，来表征云种群。 我们发现，为了准确理解云的动力学，有必要考虑总引力势能，而不仅仅是云的内部自引力。 显示英文摘要

We investigate the role of tidal forces in molecular cloud formation by examining how apparent boundedness, as diagnosed by the classical virial parameter, relates to the actual gravitational state of clouds subject to tidal forces from their environment. Clouds are identified by a dendrogram algorithm in zoom-in regions taken from a simulation of a Milky Way-mass galaxy with the Voronoi mesh code AREPO that resolves star-forming regions at sub-parsec resolution. To look at a range of environments, we use data from three different regions that evolve differently in the center, near the equivalent of the Solar circle, and the outskirts of the modeled galaxy, at three different times, each spaced 2 Myr apart. We compute the importance of tidal forces on all identified clouds. We then compare the boundedness of clouds including only their internal potentials to boundedness also including the external gravitational potential. This comparison shows that tidal forces can unbind apparently bound clouds and bind apparently unbound clouds. We characterize the cloud population by comparing their virial parameters to their surface densities, finding the ratio of the maximum to the minimum eigenvalues of the tidal tensor, and determining the strength of gravitational instability in each examined region. We find that it is necessary to take the total gravitational potential into account rather than just the internal self-gravity of the clouds to have an accurate understanding of cloud dynamics.

[25] arXiv:2507.03832 [中文pdf, pdf, html, 其他]

标题： 宇宙射线传播对暗云化学和电离分数的影响 显示英文标题

标题： Impact of cosmic-ray propagation on the chemistry and ionisation fraction of dark clouds

G. Latrille, A. Lupi, S. Bovino, T. Grassi, G. Sabatini, M. Padovani

评论： 10页，9图，1表

期刊参考： A&A 699, A126 (2025)

主题： 星系的天体物理学 (astro-ph.GA) ; 高能天体物理现象 (astro-ph.HE)

对气体云中宇宙射线电离率的正确建模对于准确描述其化学演化至关重要。 然而，这种建模计算成本较高，因为它需要在一段时间内模拟宇宙射线在整个云中的传播。 我们提出了一种更高效的方法，同时确保对宇宙射线对前恒星核化学影响的可靠估计。 我们引入了一个数值框架，模拟气体云中的宇宙射线传播，并将其应用于使用代码 GIZMO 进行的磁流体动力学模拟。 它通过计算所穿过的 H$_2$有效柱密度来模拟宇宙射线的衰减，该柱密度使用与模拟中相同的核加权方法进行估算。 然后将得到的宇宙射线电离率用于后处理，以研究云的化学演化。 我们发现宇宙射线传播显著影响氘化和非氘化物种，并且它依赖于假设的宇宙射线谱。 我们探讨了电子丰度、宇宙射线电离率和最相关离子（HCO$^+$，N$_2$H$^+$，DCO$^+$，N$_2$D$^+$，以及o-H$_2$D$^+$）的丰度之间的相关性，目的是找到将它们联系起来的简单表达式。 我们提供了一个解析公式，用于从可观察的示踪剂估计电离分数，X(e$^-$)，并将其应用于高质量云团的现有观测数据。 我们得到的数值约为 10$^{-8}$，这与之前的研究和致密云团的预期一致。 我们还提供了一个线性拟合，用于从局部H$_2$密度计算宇宙射线电离率，该拟合将用于不包含宇宙射线传播的三维模拟中。 显示英文摘要

A proper modelling of the cosmic-ray ionisation rate within gas clouds is crucial to describe their chemical evolution accurately. However, this modelling is computationally demanding because it requires the propagation of cosmic rays throughout the cloud over time. We present a more efficient approach that simultaneously guarantees a reliable estimate of the cosmic-ray impact on the chemistry of prestellar cores. We introduce a numerical framework that mimics the cosmic-ray propagation within gas clouds and applies it to magnetohydrodynamic simulations performed with the code GIZMO. It simulates the cosmic-ray attenuation by computing the effective column density of H$_2$ that is traversed, which is estimated using the same kernel weighting approach as employed in the simulation. The obtained cosmic-ray ionisation rate is then used in post-processing to study the chemical evolution of the clouds. We found that cosmic-ray propagation affects deuterated and non-deuterated species significantly and that it depends on the assumed cosmic-ray spectrum. We explored correlations between the electron abundance, the cosmic-ray ionisation rate, and the abundance of the most relevant ions (HCO$^+$, N$_2$H$^+$, DCO$^+$, N$_2$D$^+$, and o-H$_2$D$^+$), with the purpose of finding simple expressions that link them. We provide an analytical formula to estimate the ionisation fraction, X(e$^-$), from observable tracers and applied it to existing observations of high-mass clumps. We obtained values of about 10$^{-8}$, which is in line with previous works and with expectations for dense clouds. We also provide a linear fit to calculate the cosmic-ray ionisation rate from the local H$_2$ density, which is to be employed in three-dimensional simulations that do not include cosmic-ray propagation.

[26] arXiv:2507.03948 [中文pdf, pdf, html, 其他]

标题： H$β$电离区的virial因子$f$对于NGC 5548和NGC 4151的宽线区 显示英文标题

标题： The virial factor $f$ of the H$β$ Broad-line for NGC 5548 and NGC 4151

Shao-Jun Li, Xiang-Wei Ning, Yan-Song Ma, Yi Tang, Wei-Hao Bian

评论： 21页，9图，7表，已接受发表于ApJ

主题： 星系的天体物理学 (astro-ph.GA)

对两个活动星系核NGC 5548和NGC 4151的维里因子$f$的变化进行了研究，这两个星系在过去30年中已被脉冲映射（RM）超过20次。使用来自宽H$\beta$半高全宽（$\rm FWHM_{\rm H\beta} $）或平均谱或均方根谱的线性弥散度的四个速度示踪器，计算每个RM时期$f$。发现$f$与观测参数之间存在显著相关性，例如宽线宽度、爱丁顿比率和线轮廓形状。对于NGC 5548，$f \propto \rm {FWHM}_{mean}^{-0.70\pm0.13}$，对于NGC 4151，$f \propto \rm {FWHM}_{mean}^{-3.31\pm0.59}$。 这表明应包含一个变量$f$来加权virial SMBH质量。 使用厚盘宽线区（BLR）的简单模型，我们表明平均倾角的变化可以解释$f$的变化。 倾角范围为 NGC 5548 的$14.1-40.6$度和 NGC 4151 的$14.0-55.1$度。 用阻尼随机游走过程对$f$的光曲线进行建模，得到平均时间尺度为 638 和 668 天，这与 BLR 动力学时间尺度在不确定范围内一致。 这表明$f$的变化与 BLR 动力学有关，可能是由于几何形状或倾角的变化所致。 显示英文摘要

The variability of virial factor $f$ is investigated for two active galactic nucleus, NGC 5548 and NGC 4151, which had been previously reverberation mapped (RM) over 20 times in the past 30 years. Using four velocity tracers from the broad H$\beta$ width at half-maximum ($\rm FWHM_{\rm H\beta} $) or the line dispersion from the mean or rms spectra, $f$ for each RM epoch are calculated. Significant correlations are found between $f$ and observational parameters, such as the broad line widths, the Eddington ratios and the line profile shapes. For NGC 5548, $f \propto \rm {FWHM}_{mean}^{-0.70\pm0.13}$ and for NGC 4151, $f \propto \rm {FWHM}_{mean}^{-3.31\pm0.59}$. This suggests that a variable $f$ should be included to weight the virial SMBH mass. Using a simple model of thick-disc broad line regions (BLRs), we show that changes in mean inclination can explain $f$ variation. The inclination range is $14.1-40.6$ deg for NGC 5548 and $14.0-55.1$ deg for NGC 4151. Modeling the light curves of $f$ with a damped random walk process yields mean timescales of 638 and 668 days, consistent with BLR dynamical timescales within uncertainties. This indicates that $f$ variations are linked to BLR dynamics, likely due to changes in geometry or inclination.

[27] arXiv:2507.04011 [中文pdf, pdf, html, 其他]

标题： 研究z<4处小红点后代的增长与詹姆斯·韦伯空间望远镜 显示英文标题

标题： Investigating the Growth of Little Red Dot Descendants at z<4 with the JWST

Jean-Baptiste Billand, David Elbaz, Fabrizio Gentile, Maxime Tarrasse, Maximilien Franco, Benjamin Magnelli, Emanuele Daddi, Yipeng Lyu, Avishai Dekel, Fabio Pacucci, Valentina Sangalli, Mark Dickinson, Mauro Giavalisco, Benne W. Holwerda, Dale D. Kocevski, Anton M. Koekemoer, Vasily Kokorev, Ray A. Lucas, Pablo G. Pérez-González

评论： 提交至A&A

主题： 星系的天体物理学 (astro-ph.GA)

JWST最显著的发现之一是一类被称为小红点（LRDs）的紧凑红色星系。 它们的存在引发了关于其性质、起源和演化的诸多问题。 这些星系在数量密度上呈现出急剧下降——从$z=6$到$z=3$几乎下降了两个数量级。 在本研究中，我们通过在CEERS中识别候选后代星系来探索它们的潜在演化，假设了一条单一的演化路径：在红色紧凑核心周围形成蓝色恒星形成外缘。 我们的颜色-亮度选择在$z<4$处识别出与LRDs一样红的星系，并被年轻的蓝色恒星外缘包围。 形态参数是从单个Sérsic轮廓拟合中得出的；物理特性则是通过使用仅包含恒星的模型进行SED拟合获得的。 这些“后-LRD”候选星系表现出类似LRD的特征，包括$M_\ast \sim 10^{10} \ M_\odot $、中心密度（$ \Sigma_\ast \sim 10^{11} \ M_\odot \ \text{kpc}^{-2}$）、紧凑的尺寸和红色的静止框架颜色，但还增加了扩展成分。 它们在$z = 3 \pm 0.5$($ \sim 10^{-4.15} \, \text{Mpc}^{-3} $) 处的数密度与 LRDs 在$5 < z < 7$处的数密度相匹配，支持可能存在演化联系。 我们观察到外围质量分数和星系大小随红移增加——从$\sim 250$pc 在$ z = 5 $到$\sim 600$pc 在$ z = 3 $——表明整体恒星增长。 同时，核心保持红色且紧凑，但 V 形结构随着外围增长而消失。 这些发现支持一种演化情景，即 LRDs 通过冷吸积在宇宙时间中逐渐获得扩展的恒星成分。 这可能解释了它们在较低红移处观测数密度的明显下降。 显示英文摘要

One of JWST's most remarkable discoveries is a population of compact red galaxies known as Little Red Dots (LRDs). Their existence raises many questions about their nature, origin, and evolution. These galaxies show a steep decline in number density-nearly two orders of magnitude-from $z=6$ to $z=3$. In this study, we explore their potential evolution by identifying candidate descendants in CEERS, assuming a single evolutionary path: the development of a blue star-forming outskirt around the red compact core. Our color-magnitude selection identifies galaxies as red as LRDs at $z<4$, surrounded by young, blue stellar outskirts. Morphological parameters were derived from single S\'ersic profile fits; physical properties were obtained from SED fitting using a stellar-only model. These "post-LRD" candidates show LRD-like features with $M_\ast \sim 10^{10} \ M_\odot $, central densities ($ \Sigma_\ast \sim 10^{11} \ M_\odot \ \text{kpc}^{-2}$ ), compact sizes, and red rest-frame colors, but with an added extended component. Their number density at $z = 3 \pm 0.5$ ( $ \sim 10^{-4.15} \, \text{Mpc}^{-3} $) matches that of LRDs at $5 < z < 7$ , supporting a possible evolutionary link. We observe a redshift-dependent increase in outskirts mass fraction and galaxy size-from $\sim 250$ pc at $ z = 5 $ to $\sim 600$ pc at $ z = 3 $-suggesting global stellar growth. Meanwhile, the core remains red and compact, but the V-shape fades as the outskirts grow. These findings support an evolutionary scenario in which LRDs gradually acquire an extended stellar component over cosmic time by cold accretion. This may explain the apparent decline in their observed number density at lower redshift.

[28] arXiv:2507.04212 [中文pdf, pdf, html, 其他]

标题： 从最密集的星系团到最空旷的宇宙空洞：低红移下星系大小-质量关系中没有环境效应的证据 显示英文标题

标题： From the Densest Clusters to the Emptiest Voids: No Evidence For Environmental Effects on the Galaxy Size-Mass Relation at Low Redshift

Mohamed H. Abdullah, Nouran E. Abdelhamid, Rasha M. Samir, Gillian Wilson

评论： 18页，9图。提交至ApJ

主题： 星系的天体物理学 (astro-ph.GA)

我们对低红移（z <= 0.125）的星系大小-恒星质量关系（SMR）进行了全面研究，使用了来自SDSS-DR13调查的大光谱样本。 我们的目标是研究环境如何影响多个空间尺度上的星系结构特性。 根据特定恒星形成率、光学颜色和核球与总光度比对星系进行分类，使我们能够区分环境效应与星系固有特性。 我们在三种情境下研究了SMR：（1）比较极端环境中的星系大小——密集星系团与宇宙空洞；（2）分析不同质量星系团中的星系；（3）研究位于星系团不同区域（从核心到流入区）的成员星系。 在所有三种情况下，我们在固定恒星质量和星系类型下均未发现SMR与环境之间有显著依赖关系。 星系团和空洞中的星系遵循一致的SMR趋势，并且未观察到与星系团质量或星系团中心距离相关的可测量变化。 我们还确认早型星系的SMR斜率比晚型星系更陡。 值得注意的是，即使考虑到空洞中星系数量密度的不同，SMR对环境的这种一致性依赖关系仍然存在，这支持了SMR比例关系在不同环境中的普遍性。 显示英文摘要

We present a comprehensive study of the galaxy size-stellar mass relation (SMR) at low redshift (z <= 0.125), using a large spectroscopic sample from the SDSS-DR13 survey. Our goal is to investigate how environment affects galaxy structural properties across multiple spatial scales. Galaxies are classified by specific star formation rate, optical color, and bulge-to-total light ratio, allowing us to disentangle environmental effects from intrinsic galaxy properties. We examine the SMR in three contexts: (1) comparing galaxy sizes in two extreme environments-dense clusters versus cosmic voids; (2) analyzing cluster galaxies across a range of cluster masses; and (3) studying member galaxies located in different cluster regions, from the core to the infall zone. In all three cases, we find no significant dependence of the SMR on environment at fixed stellar mass and galaxy type. Cluster and void galaxies follow consistent SMR trends, and no measurable variation is observed with cluster mass or cluster-centric distance. We also confirm that early-type galaxies exhibit steeper SMR slopes than late types. Notably, this consistent lack of environmental dependence on the SMR persists even when accounting for the differing galaxy number densities in voids, supporting the universality of this SMR scaling relation across diverse environments.

[29] arXiv:2507.04320 [中文pdf, pdf, html, 其他]

标题： 一个引力加速度模型来解释双峰窄发射线的同向偏移 显示英文标题

标题： A gravitational acceleration model to explain the double-peaked narrow emission lines shifted in the same direction

XingQian Chen, GuiLin Liao, Qi Zheng, XueGuang Zhang

主题： 星系的天体物理学 (astro-ph.GA)

在本手稿中，我们首次提出了一种过度简化但可能有效的引力加速度模型，以解释在相同方向上移动的双峰窄发射线（DPNELs）。 我们采用了一个合并的千秒差距尺度双核系统的框架，该系统包含一个具有清晰窄线区（NLRs）的发射线星系，与一个缺乏发射线特征的伴星系合并。 由于两个星系对NLRs产生的引力作用，在视线方向上投影时，远侧和近侧NLR成分的加速度可能具有相同的方向矢量，导致观测到的DPNEL的速度向同一方向移动。 我们的模拟表明，在包含发射线星系的合并千秒差距尺度双核系统中，产生向同一方向移动的双峰特征的概率为5.81%。 除了我们提出的模型预期的结果外，我们识别出一个独特的星系SDSS J001050.52-103246.6，其明显的DPNELs向同一方向移动，可以通过引力加速度模型合理解释。 这个提出的模型为在千秒差距尺度双核系统中，两个星系沿视线方向对齐的情况下解释向同一方向移动的DPNELs提供了一条新的途径。 显示英文摘要

In this manuscript, we propose, for the first time, an oversimplified but potentially effective gravitational acceleration model to interpret the double-peaked narrow emission lines (DPNELs) shifted in the same direction. We adopt the framework of a merging kpc-scale dual-core system in an elliptical orbit, which has an emission-line galaxy with clear narrow line regions (NLRs) merging with a companion galaxy lacking emission line features. Due to gravitational forces induced by both galaxies on the NLRs, the accelerations of the far-side and near-side NLR components may share the same vector direction when projected along the line-of-sight, leading the velocities of the observed DPNELs to shift in the same direction. Our simulations indicate that the probability of producing double-peaked features shifted in the same direction reaches 5.81% in merging kpc-scale dual core systems containing emission-line galaxies. Besides the expected results from our proposed model, we identify a unique galaxy SDSS J001050.52-103246.6, whose apparent DPNELs shifted in the same direction can be plausibly explained by the gravitational acceleration model. This proposed model provides a new path to explain DPNELs shifted in the same direction in the scenario that the two galaxies align along the line-of-sight in kpc-scale dual-core systems.

[30] arXiv:2507.04359 [中文pdf, pdf, html, 其他]

标题： 多年ZTF数据中活动星系核的带间滞后变化 显示英文标题

标题： Interband Lag Variability in Active Galactic Nuclei across ZTF Data from Multiple Years

Zhen-Bo Su, Zhen-Yi Cai, Hengxiao Guo, Mouyuan Sun, Jun-Xian Wang

评论： 已被ApJ接受，欢迎提出意见！

主题： 星系的天体物理学 (astro-ph.GA)

活动星系核（AGN）的光学连续谱中的带间滞后现象多年来已被观测到，但其物理起源仍不清楚。 尽管在少数个别AGN中发现了可变的带间滞后，但AGN样本的带间滞后的时间行为尚未被系统地探索。 在这里，我们分析了94个明亮AGN在$z<0.8$的带间滞后，使用了Zwicky Transient Facility数据发布22中的季节性一年和完整六年$gri$-band光变曲线。 我们发现，在94个AGN中，超过一半显示出带间滞后的显著季节性变化。 此外，通过平均多个季节性光变曲线推导出的短期滞后，始终小于从完整六年光变曲线推导出的长期滞后。 这支持了最近的理论模拟，其中滞后测量对光变曲线的基线敏感，滞后变化可能仅仅是AGN变异性固有随机性的结果。 我们的发现表明，AGN的带间滞后比通常认为的更加复杂和随机，并强调了高精度时域调查在揭示AGN变异性及其相关吸积物理特性的重要性。 显示英文摘要

Interband lags in the optical continua of active galactic nuclei (AGN) have been observed over years of monitoring, yet their physical origins remain unclear. While variable interband lags have been found in a few individual AGN potentially, the temporal behavior of interband lags of an AGN sample has not been explored systematically. Here, we analyze the interband lags of 94 bright AGN at $z<0.8$, using both seasonal one-year and full six-year $gri$-band light curves from Zwicky Transient Facility Data Release 22. We find that more than half of 94 AGN show significant seasonal variations in the interband lags. Besides, the short-term lags, derived by averaging lags inferred from multiple seasonal light curves, are consistently smaller than the long-term lags, which are inferred from the full six-year light curves. This supports recent theoretical simulations where the lag measurement is sensitive to the baseline of light curve and the lag variation could be simply attributed to the inherent randomness of AGN variability. Our findings suggest that the interband lags of AGN are more complex and stochastic than commonly thought, and highlight the importance of high-precision time-domain surveys in uncovering the properties of AGN variability as well as the associated accretion physics.

[31] arXiv:2507.04530 [中文pdf, pdf, html, 其他]

标题： 附近棒旋星系中的极端云碰撞 显示英文标题

标题： Extreme cloud collisions in nearby barred galaxies

Tutku Kolcu, Mattia C. Sormani, Witold Maciejewski, Sophia K. Stuber, Eva Schinnerer, Francesca Fragkoudi, Ashley T. Barnes, Frank Bigiel, Mélanie Chevance, Dario Colombo, Éric Emsellem, Simon C. O. Glover, Jonathan D. Henshaw, Ralf S. Klessen, Sharon E. Meidt, Justus Neumann, Francesca Pinna, Miguel Querejeta, Thomas G. Williams

评论： 12页，7图，已接受发表于MNRAS

主题： 星系的天体物理学 (astro-ph.GA)

银河系内部区域已知包含一种神秘的显著分子云群体，这些分子云以极其宽广的谱线为特征。这些“扩展速度特征”（EVFs）的物理起源仍在争论中，尽管已有假说认为它们可能与银河系棒状结构的“尘埃带”有关。在本文中，我们使用PHANGS-ALMA CO(2-1)调查，在附近棒旋星系的尘埃带中寻找类似的特征。我们的目标是确认其他星系中是否存在EVFs，并利用外部视角来深入了解它们的起源。我们研究了一个包含29个棒旋星系的样本，并发现34%的星系包含一个或多个EVFs，而其余星系则没有明显的EVFs迹象。在分析EVFs的物理特性时，我们发现它们具有较大的维里参数，范围从几百到几千，表明它们处于强烈的非平衡状态。它们起源的最可能解释是极端的云-云碰撞，相对速度超过100km/s，在由棒驱动的高度非圆周流动中发生。这一解释与银河系中的先前高分辨率观测结果一致。来自PHANGS-JWST储藏调查的高灵敏度红外观测进一步证实了这一解释，这些观测揭示了气体流，似乎在EVFs存在的位置撞击尘埃带。我们认为EVFs是文献中最为清晰的云-云碰撞实例，并代表了一个研究云碰撞及其对恒星形成影响的独特机会。 显示英文摘要

The inner regions of the Milky Way are known to contain an enigmatic population of prominent molecular clouds characterised by extremely broad lines. The physical origin of these ''extended velocity features'' (EVFs) is still debated, although a connection with the ''dust lanes'' of the Galactic bar has been hypothesised. In this paper, we search for analogous features in the dust lanes of nearby barred galaxies using the PHANGS-ALMA CO(2-1) survey. We aim to confirm existence of EVFs in other galaxies and to take advantage of the external perspective to gain insight into their origin. We study a sample of 29 barred galaxies and find that 34% contain one or more EVFs, while the remaining lack obvious signs of EVFs. Upon analysing the physical properties of the EVFs, we find they possess large virial parameters, ranging from few hundreds to several thousand, indicating that they are strongly out-of-equilibrium. The most likely explanation for their origin is extreme cloud-cloud collisions with relative velocities in excess of 100km/s in highly non-circular flow driven by the bar. This interpretation is consistent with previous high-resolution observations in Milky Way. Further corroboration of this interpretation comes from the inspection of high-sensitivity infrared observations from the PHANGS-JWST Treasury Survey that reveals streams of gas that appear to be hitting the dust lanes at locations where EVFs are found. We argue that EVFs are the clearest examples of cloud-cloud collisions available in literature and represent a unique opportunity to study cloud collisions and their impact on star formation.

[32] arXiv:2507.04703 [中文pdf, pdf, html, 其他]

标题： 早期型星系NGC 2768的深中性氢观测：被新发现的卫星星系碰撞了吗？ 显示英文标题

标题： Deep neutral hydrogen observations of the early-type galaxy NGC 2768: collided by a newly discovered satellite galaxy?

Nai-Ping Yu, Ming Zhu, Jin-Long Xu, Chuan-Peng Zhang, Xiao-Lan Liu, Peng Jiang

主题： 星系的天体物理学 (astro-ph.GA)

我们介绍了使用五百米口径球面射电望远镜（FAST）对早型星系NGC 2768进行的深度中性氢（Hi）观测结果。 利用FAST的高灵敏度，我们发现NGC 2768周围存在一个扩展的气体包层。 总Hi质量测量为8.1 x 10^8 M_sun ，与之前的韦斯特博克综合射电望远镜（WSRT）研究相比有了数量级的增加。 位置-速度（PV）图表明该包层主要包含两个成分：NGC 2768的Hi盘和一个新发现的卫星星系，在目前的深光学巡天中没有可检测的对应物。 气体盘的中心与NGC 2768的光学盘不对齐，更多的气体呈现红移，表明它已被扰动。 我们的研究显示NGC 2768目前正处于从螺旋星系向S0星系过渡的过程中。 之前的深度WSRT观测揭示了包层中心的两个致密云块（本文中称为云块A和云块B）。 我们发现云块A对应于盘最致密的部分，而云块B可能是一个新发现的卫星星系，可能在约0.38 Gyr前与NGC 2768发生碰撞。 我们还发现了云块B与PGC 2599651、NGC 2768与UGC 4808之间的潮汐相互作用。 基于这些新发现，我们最终分析了NGC 2768的分层吸积历史。 显示英文摘要

We present the results of a deep neutral hydrogen (Hi) observation of the early-type galaxy NGC 2768 using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Leveraging the high sensitivity of FAST, we discover an extended gas envelope around NGC 2768. The total Hi mass is measured to be 8.1 x 10^8 M_sun , representing a magnitude increase compared to previous Westerbork Synthesis Radio Telescope (WSRT) studies. Position-velocity (PV) diagram indicates the envelope mainly involves two components: an Hi disk of NGC 2768 and a newly discovered satellite galaxy without detectable counterparts in currently deep optical surveys. The center of the gas disk is mis-aligned with the optical disk of NGC 2768, with more gas redshifted, indicating it has been disturbed. Our study indicates NGC 2768 is currently undergoing a transition from a spiral galaxy to an S0. Previous deep WSRT observations reveal two dense clumps (named as Clumps A and Clump B throughout this paper) in the center of the envelope. We find Clump A corresponds to the densest part of the disk, while Clump B might be a newly discovered satellite galaxy which probably collided NGC 2768 about 0.38 Gyr ago. We also find tidal interactions between Clump B and PGC 2599651, NGC 2768 and UGC 4808. Based on these new findings, we finally analyze hierarchical accretion history of NGC 2768.

[33] arXiv:2507.04757 [中文pdf, pdf, html, 其他]

标题： 银河系、大麦云、M31和M33中非常长周期造父变星的SEDs 显示英文标题

标题： The SEDs of very long-period cepheids in the Milky Way, the Magellanic Clouds, M31 and M33

Martin Groenewegen

期刊参考： 2025，A&A 699，A102

主题： 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

光谱能量分布（SEDs）的20个银河系（MW）、9个大麦哲伦星系（LMC）、7个小麦哲伦星系（SMC）、12个M31和7个M33（经典）造父变星，其周期超过50天，使用文献中的测光数据构建，并用模型大气进行拟合，目的是识别具有红外过量的天体。 SEDs用恒星光球模型进行拟合，以推导出最佳拟合的光度和有效温度；在需要时添加尘埃成分。 距离和消光值取自文献。 检查了WISE和IRAC图像，以验证潜在的过量辐射是否与中心天体有关。 只在LMC中发现了一个具有显著红外（IR）过量的恒星，而在SMC、M31和M33中没有发现，这与早期关于银河系的研究结果相反，该研究认为红外过量可能在银河系造父变星中比在麦哲伦星系中更明显。 在银河系中还发现了一个额外的天体具有红外过量，但尚不清楚它是经典造父变星还是类型-{\sc 二} 造父变星。 这些恒星绘制在赫茨普龙-罗素图（HRD）中，并与经典造父变星的演化轨迹以及理论不稳定带进行比较。 对于大多数恒星，它们在HRD中的位置与不稳定带一致。 对于银河系中的恒星，距离和消光的不确定性可能会显著改变它们在HRD中的位置。 显示英文摘要

The spectral energy distributions (SEDs) of 20 Milky Way (MW), 9 Large Magellanic Cloud (LMC), 7 Small Magellanic Cloud (SMC), 12 M31, and 7 M33 (classical) Cepheids with periods longer than 50 days were constructed using photometric data from the literature and fitted with model atmospheres with the aim of identifying objects with an infrared excess. The SEDs were fitted with stellar photosphere models to derive the best-fitting luminosity and effective temperature; a dust component was added when required. The distance and reddening values were taken from the literature. WISE and IRAC images were inspected to verify whether potential excess emission was related to the central objects. Only one star with a significant infrared (IR) excess was found in the LMC and none in the SMC, M31, and M33, contrary to earlier work on the MW suggesting that IR excess may be more prominent in MW Cepheids than in the Magellanic Clouds. One additional object in the MW was found to have an IR excess, but it is unclear whether it is a classical Cepheid or a type-{\sc ii} Cepheid. The stars were plotted in a Hertzsprung--Russell diagram (HRD) and compared to evolutionary tracks for CCs and to theoretical instability strips. For the large majority of stars, the position in the HRD is consistent with the instability strip. For stars in the MW uncertainties in the distance and reddening can significantly change their position in the HRD.

[34] arXiv:2507.04825 [中文pdf, pdf, html, 其他]

标题： 去氘化氨在预恒星核心L1544中的统计核自旋比 显示英文标题

标题： Statistical nuclear spin ratios of deuterated ammonia in the pre-stellar core L1544

Jorma Harju (1,2), Paola Caselli (1), Olli Sipilae (1), Silvia Spezzano (1), Arnaud Belloche (3), Luca Bizzocchi (4), Jaime Pineda (1), Elena Redaelli (5,1), Friedrich Wyrowski (3) ((1) Max-Planck-Institut fuer extraterrestrische Physik, (2) Department of Physics, University of Helsinki, (3) Max-Planck-Institut fuer Radioastronomie, (4) Dipartimento di Chimica, Universita di Bologna, (5) European Southern Observatory)

评论： 已被接受发表于《天文学与天体物理学》

主题： 星系的天体物理学 (astro-ph.GA)

我们确定了典型预星云核L1544中NH2D和NHD2的ortho/para (o/p)比率。 该核心使用APEX和IRAM 30米望远镜观测了ortho-和para-NH2D的两个最低旋转谱线。 ortho-和para-NHD2的基态谱线使用APEX进行了观测。 核心中的化学丰度分布是通过一个气体-尘埃化学模型预测的，该模型考虑了气体中质子转移反应的两种不同情景。 其中一种情景，所谓的完全混合（FS），允许质子和氘在解离前在中间反应复合物中完全混合，而另一种则将这些反应描述为质子或氘的跳跃（PH）。 我们还测试了与化学模型无关的假设丰度分布。 辐射转移计算用于从预测和假设的丰度分布中模拟观测到的NH2D和NHD2谱线。 我们的建模结果表明，波长为0.9毫米的NH2D和NHD2基态谱线，由于使用相同的光束和同一光谱仪带宽可观测到，是最可靠的o/p比率探测器。 使用PH反应方案的模拟比使用FS模型的模拟与观测结果有更一致的匹配。 使用随气体密度变化的分段幂律丰度分布进行的模拟给出的自旋比率接近PH情景的预测：o/p-NH2D=2.85±0.05，o/p-NHD2=2.10±0.06（1 sigma）。 气体相中PH情景预测的o/p比率对应于核自旋统计权重，即o/p-NH2D=3，o/p-NHD2=2。 考虑到在尘埃表面的H和D原子加成反应也会导致这些比率，合理地假设星际氨及其氘化形式的自旋比率通常等于它们的统计值。 显示英文摘要

We determined the ortho/para (o/p) ratios of NH2D and NHD2 in the archetypical pre-stellar core L1544. The core was observed in the two lowest rotational lines of ortho- and para-NH2D using the APEX and the IRAM 30 m telescopes. The ground-state lines of ortho- and para-NHD2 were observed with APEX. The distributions of chemical abundances in the core were predicted using a gas-grain chemistry model with two different scenarios concerning proton transfer reactions in the gas. One of the scenarios, the so-called full scrambling (FS), allows protons and deuterons to be completely mixed in the intermediate reaction complex before dissociation, whereas the other describes these reactions as proton or deuteron hops (PH). We also tested assumed abundance profiles independent of the chemistry models. Radiative transfer calculations were used to simulate the observed NH2D and NHD2 lines from the predicted and assumed abundance profiles. Our modelling efforts suggest that the ground-state lines of NH2D and NHD2 at the wavelength 0.9 mm that are observable with the same beam and in the same spectrometer band are the most reliable probes of the o/p ratios. Simulations using the PH reaction scheme show systematically better agreement with the observations than simulations with the FS model. Simulations using a broken power law abundance profile as a function of the gas density give spin ratios that are close to the predictions of the PH scenario: o/p-NH2D=2.85+-0.05, o/p-NHD2=2.10+-0.06 (1 sigma). The o/p ratios predicted by the PH scenario in the gas phase correspond to the nuclear spin statistical weights, that is, o/p-NH2D=3, o/p-NHD2=2. In view of the fact that H and D atom addition reactions on grain surfaces also result in these ratios, it is reasonable to assume that the spin ratios of interstellar ammonia and its deuterated forms are in general equal to their statistical values.

[35] arXiv:2507.04913 [中文pdf, pdf, html, 其他]

标题： 射电连续谱中大质量原恒星的圆偏振首次检测 显示英文标题

标题： First detection of Circular Polarization in radio continuum towards a Massive Protostar

A. G. Cheriyan, S. Vig, Nirupam Roy, Samir Mandal, C. Carrasco-González, A. Rodríguez-Kamenetzky, A. Pasetto

评论： 11页，6图，已接受发表于《天体物理杂志快报》

主题： 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

极化测量为恒星形成系统中的磁场提供了强有力的约束。 虽然已经在低质量原恒星表面附近获得了几kG（kG）的磁场估计值，但在大质量原恒星表面附近却没有类似的测量结果。 我们首次利用卡尔·G·扬斯基甚大阵列（VLA）观测数据对大质量原恒星IRAS 18162-2048进行了射电连续谱圆偏振（CP）的测量。 在观测频率范围$4-6$GHz 内，分数CP在$3-5\%$之间变化。 我们考虑了多种产生CP的假设，并提出（i）回旋同步辐射和（ii）磁介质中湍流引起的法拉第转换——均由轻微相对论电子驱动——作为可能的机制。 我们首次估计了靠近大质量原恒星的磁场$B\gtrsim20-35$G。 根据我们的观测，低能电子的洛伦兹因子估计在 gyrosynchrotron 辐射范围内为$\gamma_{min}\sim5-7$，在法拉第转换范围内为$80-100$。 该磁场估计可以为大质量恒星的形成模型提供重要的约束。 显示英文摘要

Polarization measurements provide strong constraints on magnetic fields in star-forming systems. While magnetic field estimates of a few kiloGauss (kG) have been obtained near the surface of low-mass protostars, there are no analogous measurements in the immediate vicinity of the surface of massive protostars. We report the measurement of radio continuum circular polarization (CP) towards a massive protostar IRAS 18162-2048 for the first time wielding Karl G. Jansky Very Large Array (VLA) observations. The fractional CP varies between $3-5\%$ across the observed frequency range of $4-6$ GHz. We consider multiple hypotheses for the production of CP and propose (i) gyrosynchrotron emission and (ii) Faraday conversion due to turbulence in the magnetic medium - both driven by mildly relativistic electrons as plausible mechanisms. We estimate, for the first time, a magnetic field $B\gtrsim20-35$ G close to the massive protostar. The Lorentz factor of the low energy electrons is estimated to be in the range $\gamma_{min}\sim5-7$ for gyrosynchrotron emission and $80-100$ for Faraday conversion from our observations. The magnetic field estimate can provide important constraints to the formation models of massive stars.

[36] arXiv:2507.04927 [中文pdf, pdf, html, 其他]

标题： 介绍Phoebos模拟：星系形成初期的星系特性 显示英文标题

标题： Introducing the Phoebos simulation: galaxy properties at the dawn of galaxy formation

Floor van Donkelaar, Pedro R. Capelo, Lucio Mayer, Darren S. Reed, Thomas R. Quinn

评论： 22页，20图，提交至MNRAS

主题： 星系的天体物理学 (astro-ph.GA) ; 宇宙学与非星系天体物理学 (astro-ph.CO)

詹姆斯·韦布空间望远镜（JWST）现在使我们能够以前所未有的细节观察宇宙黎明末期（$z \sim 10-15$）的星系，揭示它们的形态、大小和内部结构。 这些观测为驱动早期星系形成的过程提供了关键见解。 在本研究中，我们介绍了Phoebos流体动力学宇宙学模拟，这是一个最先进的100 Mpc体积，旨在研究宇宙黎明末期及再电离时期星系的形成和演化。 Phoebos包含一个有意设计得较弱的恒星反馈模型，以解决JWST在早期宇宙中看到的大量大质量星系的问题。 与大多数大型宇宙流体动力学模拟不同，我们没有采用有效状态方程模型，而是我们的辐射冷却模型使我们能够捕捉星系内外气体的多相性质。 Phoebos在$z \gtrsim 8$重现了早期星系形成的关键可观测量，包括恒星质量函数和恒星质量与晕质量的关系。 它还恢复了恒星大小与质量关系的观测斜率，并与特定恒星形成率非常吻合。 这些结果表明，在仅有轻微恒星反馈调节的情况下，高效的恒星形成驱动了早期星系的增长，支持了宇宙黎明期间快速恒星质量组装的情景。 宇宙恒星形成密度有迹象表明，在较低红移时， Phoebos可能会高估系统内的恒星质量，这表明为了再现后期观测，可能需要转向更强的恒星反馈。 这些结果突显了Phoebos解释JWST观测和探索塑造星系形成的演化物理过程的潜力。 显示英文摘要

The James Webb Space Telescope (JWST) now allows us to observe galaxies at the end of cosmic dawn ($z \sim 10-15$) with unprecedented detail, revealing their morphologies, sizes, and internal structures. These observations offer crucial insights into the physical processes driving early galaxy formation. In this work, we introduce the Phoebos hydrodynamical cosmological simulation, a state-of-the-art 100 Mpc volume designed to study the formation and evolution of galaxies at the end of cosmic dawn and into the epoch of reionization. Phoebos includes a stellar feedback model that is intentionally weak, in order to address the high abundance of massive galaxies seen by JWST at early epochs. At variance with most large cosmological hydrodynamical simulations, we do not employ an effective equation of state model, instead our radiative cooling model allows us to capture the multi-phase nature of the gas inside and around galaxies. Phoebos reproduces key observables of early galaxy formation at $z \gtrsim 8$, including the stellar mass function and the stellar-to-halo mass relation. It also recovers the observed slope of the stellar size-to-mass relation and matches the specific star formation rate remarkably well. These results suggest that highly efficient star formation in the presence of only mild regulation from stellar feedback, drives early galaxy growth, supporting a scenario of rapid stellar mass assembly during cosmic dawn. There are indications in the cosmic star formation density that, at lower redshifts, Phoebos might overpredict the stellar mass within the systems, suggesting that a transition to a stronger stellar feedback may be necessary to reproduce later-time observations. These results highlight the potential of Phoebos to interpret JWST observations and to probe the evolving physical processes that shape galaxy formation.

[37] arXiv:2507.05016 [中文pdf, pdf, html, 其他]

标题： 中心集中恒星形成在年轻星团中 显示英文标题

标题： Centrally concentrated star formation in young clusters

Adilkhan Assilkhan, Mordecai-Mark Mac Low, Brooke Polak, Ernazar Abdikamalov, Claude Cournoyer-Cloutier, Sean C. Lewis, Mukhagali Kalambay, Aigerim Otebay, Bekdaulet Shukirgaliyev

评论： 提交至A&A发表。13页，10图，2表。欢迎提出意见和建议（包括缺失的参考文献）

主题： 星系的天体物理学 (astro-ph.GA)

研究星团演化需要模拟其密度分布如何从原始气体分布发展而来。 观测证据表明，许多星团遵循普尔默密度分布。 然而，大多数研究集中在气体散失之后的阶段，忽略了气体对早期动力学演化的影响。 我们研究了在气体云中形成的星团的发展，特别是那些具有中心集中气体分布的星团。 模拟是使用\texttt{火炬}框架进行的，将\texttt{快速访问存储器}磁流体动力学代码集成到\texttt{AMUSE}中。 这使得可以详细模拟恒星形成、恒星演化、恒星动力学、辐射转移和气体磁流体动力学。 我们研究了总质量为$2.5\times 10^3\, M_\odot$的中心集中、湍流球体的坍缩，调查了不同数值分辨率和恒星形成情景的影响。 云中心的自由下落时间比边缘更短，最小值为$0.55\,\mathrm{Myr}$。 本研究的主要结论是：(1) 即使在致密气体云中，子星团最初也会形成；(2) 最终的恒星密度分布与普尔默分布一致，但比解析预测的更集中；(3) 气体在中心自由下落时间尺度上整体向中心坍缩，这与解析模型中局部碎片化和恒星形成的假设相矛盾；(4) 因此，气体主要从最内层区域被驱散；(5) 最终的恒星形成效率 (SFE) 取决于最大质量恒星的质量和形成时间以及整体恒星形成时间尺度。 显示英文摘要

The study of star cluster evolution necessitates modeling how their density profiles develop from their natal gas distribution. Observational evidence indicates that many star clusters follow a Plummer density profile. However, most studies have focused on the phase after gas ejection, neglecting the influence of gas on early dynamical evolution. We investigate the development of star clusters forming within gas clouds, particularly those with a centrally concentrated gas profile. Simulations were conducted using the \texttt{Torch} framework, integrating the \texttt{FLASH} magnetohydrodynamics code into \texttt{AMUSE}. This permits detailed modeling of star formation, stellar evolution, stellar dynamics, radiative transfer, and gas magnetohydrodynamics. We study the collapse of centrally concentrated, turbulent spheres with a total mass of $2.5\times 10^3\, M_\odot$, investigating the effects of varying numerical resolution and star formation scenarios. The free-fall time is shorter at the center than at the edges of the cloud, with a minimum value of $0.55\,\mathrm{Myr}$. The key conclusions from this study are: (1) subclusters initially form even in dense gas clouds; (2) the final stellar density profile is consistent with a Plummer profile, but more centrally concentrated than analytically predicted; (3) gas collapses globally toward the center on the central free-fall time scale, contradicting the assumption in analytical models of local fragmentation and star formation; (4) hence, gas is predominantly ejected from the innermost regions; and (5) the final value of the SFE depends on the mass and formation time of the most massive star as well as the overall star formation timescale.

[38] arXiv:2507.05060 [中文pdf, pdf, html, 其他]

标题： 一个用于银河系化学演化中模型比较和基于模拟的推断的指南 显示英文标题

标题： A COMPASS to Model Comparison and Simulation-Based Inference in Galactic Chemical Evolution

Berkay Gunes, Sven Buder, Tobias Buck

评论： 已被2025年机器学习在天体物理学研讨会接收

主题： 星系的天体物理学 (astro-ph.GA) ; 天体物理学的仪器与方法 (astro-ph.IM) ; 机器学习 (cs.LG) ; 计算物理 (physics.comp-ph) ; 数据分析、统计与概率 (physics.data-an)

我们提出\texttt{指南针}，一种基于仿真的推断框架，该框架将基于得分的扩散模型与变压器架构相结合，在竞争性的银河系化学演化（GCE）模型中联合执行参数估计和贝叶斯模型比较。\texttt{指南针}处理高维、不完整和可变大小的恒星丰度数据集。 应用到高精度元素丰度测量，\texttt{指南针}评估40种核合成产率表的组合。该模型强烈偏好 NuGrid 的渐近巨星分支产率和 IllustrisTNG 模拟中使用的核心坍缩超新星产率，实现了接近于一的累积后验概率。 使用首选模型，我们推断出陡峭的高质量初始质量函数斜率和升高的 Ia 型超新星归一化值，这与先前的太阳邻域研究一致，但现在是从完全摊销的贝叶斯推断中得出的。 我们的结果表明，现代的 SBI 方法可以稳健地约束天体物理模拟器中的不确定物理，并在分析复杂仿真数据时实现有原则的模型选择。 显示英文摘要

We present \texttt{COMPASS}, a novel simulation-based inference framework that combines score-based diffusion models with transformer architectures to jointly perform parameter estimation and Bayesian model comparison across competing Galactic Chemical Evolution (GCE) models. \texttt{COMPASS} handles high-dimensional, incomplete, and variable-size stellar abundance datasets. % Applied to high-precision elemental abundance measurements, \texttt{COMPASS} evaluates 40 combinations of nucleosynthetic yield tables. The model strongly favours Asymptotic Giant Branch yields from NuGrid and core-collapse SN yields used in the IllustrisTNG simulation, achieving near-unity cumulative posterior probability. Using the preferred model, we infer a steep high-mass IMF slope and an elevated Supernova\,Ia normalization, consistent with prior solar neighbourhood studies but now derived from fully amortized Bayesian inference. % Our results demonstrate that modern SBI methods can robustly constrain uncertain physics in astrophysical simulators and enable principled model selection when analysing complex, simulation-based data.

[39] arXiv:2507.05176 [中文pdf, pdf, html, 其他]

标题： 大晕团属性的Mass Proxy质量在IllustrisTNG和FLAMINGO模拟中：I. 热气体 显示英文标题

标题： Mass Proxy Quality of Massive Halo Properties in the IllustrisTNG and FLAMINGO Simulations: I. Hot Gas

Eddie Aljamal, August E. Evrard, Arya Farahi, Annalisa Pillepich, Dylan Nelson, Joop Schaye, Matthieu Schaller, Joey Braspenning

评论： 23页，14图

主题： 星系的天体物理学 (astro-ph.GA) ; 宇宙学与非星系天体物理学 (astro-ph.CO)

我们研究了由IllustrisTNG、TNG-Cluster和FLAMINGO宇宙学流体动力学模拟实现的两个大群集和团尺度晕样本的五个热气体属性的质量-属性关系（MPRs）的尺度和红移依赖性。 对于i) 热气体质量（$M_{\rm gas}$）、ii) 类光谱温度（$T_{\rm sl}$）、iii) 软带X射线光度（$L_{\rm X}$）和iv) X射线（$Y_{\rm X}$）以及v）Sunyaev-Zel'dovich（$Y_{\rm SZ}$）热能的固有属性，我们使用MPR参数来推断质量代理质量（MPQ）——在给定属性下总晕质量的暗示散度——对于红移为$M_{\rm 500c} \geq 10^{13}{\, {\rm M}_\odot}$的晕而言，红移为$z \in \{0, 0.5, 1, 2\}$。 我们发现：(1) 一般来说，标度关系斜率和协方差对晕质量表现出中等至强依赖性，红移依赖性其次，(2) 对于具有$M_{\rm 500c} > 10^{14}{\, {\rm M}_\odot}$的晕，$M_{\rm gas}$和$Y_{\rm SZ}$的标度趋于自相似斜率和恒定的内在散布（分别为5%和10%），几乎与尺度无关，使这两种测量方法非常适合在$z=2$范围内进行簇的寻找和表征，(3) 在固定晕质量下，热气体质量和热能的晕质量条件似然函数紧密遵循对数正态形式，(4) 尽管归一化差异高达$0.4$个数量级，但两种模拟的尺度依赖斜率和属性协方差之间存在良好的定性，且经常是定量的一致性。在群尺度上，斜率显示出显著的红移依赖性，而散布的红移依赖性仅出现在低质量 FLAMINGO 晕中，(5) 属性相关性在两种模拟中基本一致，其值主要与现有的经验测量结果一致。我们最后进行了一项文献调查，将我们的 MPR 斜率和内在散布估计置于背景中。 显示英文摘要

We examine scale and redshift dependence of mass-property relations (MPRs) for five hot gas properties of two large group- and cluster-scale halo samples realized by the IllustrisTNG, TNG-Cluster and FLAMINGO cosmological hydrodynamical simulations. For intrinsic properties of i) hot gas mass ($M_{\rm gas}$), ii) spectroscopic-like temperature ($T_{\rm sl}$), iii) soft-band X-ray luminosity ($L_{\rm X}$), and iv) X-ray ($Y_{\rm X}$) and v) Sunyaev-Zel'dovich ($Y_{\rm SZ}$) thermal energies, we use MPR parameters to infer mass proxy quality (MPQ) -- the implied scatter in total halo mass conditioned on a property -- for halos with $M_{\rm 500c} \geq 10^{13}{\, {\rm M}_\odot}$ at redshifts, $z \in \{0, 0.5, 1, 2\}$. We find: (1) in general, scaling relation slopes and covariance display moderate to strong dependence on halo mass, with redshift dependence secondary, (2) for halos with $M_{\rm 500c} > 10^{14}{\, {\rm M}_\odot}$, scalings of $M_{\rm gas}$ and $Y_{\rm SZ}$ simplify toward self-similar slope and constant intrinsic scatter (5 and 10%, respectively) nearly independent of scale, making both measures ideal for cluster finding and characterization to $z=2$, (3) halo mass-conditioned likelihoods of hot gas mass and thermal energy at fixed halo mass closely follow a log-normal form, (4) despite normalization differences ranging up to $0.4$ dex, there is good qualitative, and often quantitative, agreement between the scale-dependent slopes and property covariance of the two simulations. Slopes show appreciable redshift dependence at the group scale, while redshift dependence of the scatter is exhibited by low mass FLAMINGO halos only, (5) property correlations are largely consistent between the simulations, with values that mainly agree with existing empirical measurements. We close with a literature survey placing our MPR slopes and intrinsic scatter estimates into context.

[40] arXiv:2507.05217 [中文pdf, pdf, html, 其他]

标题： 银河星云的定量形态学在深度光学成像中 显示英文标题

标题： Quantitative Morphology of Galactic Cirrus in Deep Optical Imaging

Qing Liu, Peter Martin, Roberto Abraham, Pieter van Dokkum, Henk Hoekstra, Juan Miró-Carretero, William Bowman, Steven Janssens, Seery Chen, Deborah Lokhorst, Imad Pasha, Zili Shen

评论： 30页，28幅图。已提交至《天文学与天体物理学》（A&A）。欢迎提出意见

主题： 星系的天体物理学 (astro-ph.GA) ; 宇宙学与非星系天体物理学 (astro-ph.CO)

光学银河尘埃云的成像，即弥漫银河光的空间解析形式，为了解银河系中弥漫星际介质（ISM）的特性提供了重要的见解。尽管之前的研究主要集中在光学尘埃云的强度特征上，但它们的形态学特性仍大多未被探索。在本研究中，我们采用几种互补的统计方法——局部强度统计、角度功率谱/$\Delta$-方差分析和小波散射变换分析——来表征深空光学成像数据中的尘埃云形态。我们通过将使用Dragonfly望远镜阵列看到的尘埃云形态与在更长波长工作的空间设施（Herschel 250~$\mu m$，WISE 12~$\mu m$和Planck辐射率）看到的形态进行比较，以及与DHIGLS{\HI }柱密度图中看到的结构进行比较，将对光学尘埃云的研究置于多波长背景下。我们的统计方法量化了这些数据集中尘埃云形态的相似性和差异性。在可见波长下，尘埃云的形态比中红外尘埃云更接近远红外尘埃云的形态；在小尺度上，宇宙红外背景的各向异性和系统误差可能导致差异。在所有尘埃示踪器中，尘埃云的形态可以用一个具有共同幂律指数$\gamma\sim-2.9$的功率谱很好地描述。我们定量地证明了光学尘埃云在广泛的角尺度上表现出丝状和相干结构。我们的结果为将光学尘埃云中相干结构的分析与塑造它们的星际介质中的基本物理过程联系起来提供了有希望的途径。此外，我们证明这些形态特征可以用来区分和解开尘埃云与河外光。 显示英文摘要

Imaging of optical Galactic cirrus, the spatially resolved form of diffuse Galactic light, provides important insights into the properties of the diffuse interstellar medium (ISM) in the Milky Way. While previous investigations have focused mainly on the intensity characteristics of optical cirrus, their morphological properties remain largely unexplored. In this study, we employ several complementary statistical approaches -- local intensity statistics, angular power spectrum / $\Delta$-variance analysis, and Wavelet Scattering Transform analysis -- to characterize the morphology of cirrus in deep optical imaging data. We place our investigation of optical cirrus into a multi-wavelength context by comparing the morphology of cirrus seen with the Dragonfly Telephoto Array to that seen with space-based facilities working at longer wavelengths (Herschel 250~$\mu m$, WISE 12~$\mu m$, and Planck radiance), as well as with structures seen in the DHIGLS {\HI} column density map. Our statistical methods quantify the similarities and the differences of cirrus morphology in all these datasets. The morphology of cirrus at visible wavelengths resembles that of far-infrared cirrus more closely than that of mid-infrared cirrus; on small scales, anisotropies in the cosmic infrared background and systematics may lead to differences. Across all dust tracers, cirrus morphology can be well described by a power spectrum with a common power-law index $\gamma\sim-2.9$. We demonstrate quantitatively that optical cirrus exhibits filamentary, coherent structures across a broad range of angular scales. Our results offer promising avenues for linking the analysis of coherent structures in optical cirrus to the underlying physical processes in the ISM that shape them. Furthermore, we demonstrate that these morphological signatures can be leveraged to distinguish and disentangle cirrus from extragalactic light.

[41] arXiv:2507.05239 [中文pdf, pdf, html, 其他]

标题： 用模拟恒星晕约束银河系晕吸积历史：设计HALO7D-X调查 显示英文标题

标题： Constraining the Milky Way Halo Accretion History With Simulated Stellar Halos: Designing the HALO7D-X Survey

Miranda Apfel, Kevin A. McKinnon, Constance M. Rockosi, Puragra Guhathakurta, Kathryn V. Johnston

评论： 23页，15图，3表

主题： 星系的天体物理学 (astro-ph.GA) ; 应用 (stat.AP)

我们介绍了HALO7D-X的设计，这是一个对恒星晕的调查，用于研究银河系的吸积历史。 该调查将结合哈勃空间望远镜（HST）和盖亚（Gaia）数据，用于天空位置和暗弱恒星（18<G<21.5星等）的自行运动，而视线速度、距离、[Fe/H]和[alpha/Fe]将使用后续的凯克光谱观测进行测量。 该调查将覆盖30条视线，由多个HST档案字段组成，并针对凯克DEIMOS光谱仪进行了优化。 我们使用布洛克和约翰斯顿恒星晕模拟的模拟调查观测，来研究HALO7D-X对约束银河系恒星晕吸积历史的基本参数的敏感性。 我们发现，我们对恒星晕前体的质量分布和吸积时间线是敏感的，但对其轨道圆度不敏感。 我们发现，模拟的晕可以基于我们调查的可观测维度分布的相似性分为三个不同的组。 这些组在它们的前体卫星的质量分布和吸积时间线上也彼此不同，这表明通过在不同晕中使用可观测值的相似性，我们可以识别它们的吸积历史的相似性。 通过HALO7D-X，我们将真实银河系数据与模拟晕进行比较，并利用可观测值与前体质量及吸积时间线之间的联系来了解我们银河系恒星晕的形成。 显示英文摘要

We present the design for HALO7D-X, a survey of the stellar halo to investigate the accretion history of the Milky Way. The survey will use a combination of Hubble Space Telescope (HST) and Gaia data for sky position and proper motions of faint stars (18<G<21.5 mag), while line-of-sight velocity, distance, [Fe/H], and [alpha/Fe] will be measured using follow-up Keck spectroscopy. The survey will cover 30 lines of sight, made up of multiple HST archival fields and optimized for Keck DEIMOS spectroscopy. We use mock survey observations of the Bullock and Johnston stellar halo simulations to investigate the sensitivity of HALO7D-X to constrain the basic parameters of the accretion history of our Galaxy's stellar halo. We find that we are sensitive to the mass distribution and accretion timeline of the stellar halo progenitors, but not their orbital circularity. We find that the simulated halos fall into three different groups based on the similarities in their distributions of the observable dimensions of our survey. These groups are also distinct from each other in the mass distribution and accretion timeline of their progenitor satellites, showing that by using similarities in our observables among halos, we are able to identify similarities in their accretion histories. With HALO7D-X we will compare real Milky Way data with simulated halos and use this connection between observables and progenitor mass and accretion timeline to learn about the formation of our Galaxy's stellar halo.

[42] arXiv:2507.05250 [中文pdf, pdf, html, 其他]

标题： 高分辨率搜寻合并中的双活动星系核：利用凯克自适应光学推进前沿 显示英文标题

标题： A High Resolution Search for Dual AGNs in Mergers: Pushing the Frontier with Keck AO

Camilo Vazquez, S. Satyapal, G. Canalizo, N. J. Secrest, R. W. Pfeifle, T. Bohn, K. Nyland, A. Aravindan, L. Blecha, J. M. Cann, S. Doan, E. K. Hicks, P. Kurczynski, S. Juneau, M. Malkan, M. McDonald, J. McKaig, P. Nair, B. Rothberg, E. Schwartzman, F. Muller-Sanchez, R. Sexton, V. U

评论： 欢迎评论

主题： 星系的天体物理学 (astro-ph.GA)

吸积的超大质量黑洞（SMBH）在星系合并中分离距离为$<$1kpc的情况下，对于理解SMBH的增长、星系演化以及SMBH双星的演化至关重要。尽管它们的重要性，已知的却不到几个，而且大多数都是偶然发现的。在本研究中，我们采用一种新的选择方法，系统地预选出可能包含亚角秒尺度未解析结构的先进合并候选体。通过利用广域红外巡天探测器（WISE）和斯隆数字天空调查（SDSS）的大调查区域和天体测量精度，我们识别出一个48个附近的先进合并样本，这些样本具有红色的WISE颜色（$W_1-W_2>0.5$），表明有吸积活动，并且其光学和红外坐标之间存在显著的亚角秒偏移，这是由SDSS和WISE测量的。我们使用凯克望远镜的NIRC2相机在$K_p$波段（$2.124 ~ \mu m$，$\Delta\lambda = 0.351 \mu m$）对这个样本进行了高分辨率自适应光学（AO）观测，以寻找由光学到红外偏移所暗示的先前未解析的结构。我们发现样本中有很大一部分（20/48或42%）显示出追踪SDSS/WISE偏移且未被SDSS解析的结构，这表明我们的方法是一种在后续光谱学中寻找双AGN的有希望的途径。档案中的光学哈勃空间望远镜（HST）成像显示，用凯克识别的结构常常在光学中被遗漏或由于部分遮挡而被错误识别，这强调了在红外中进行晚期合并研究的重要性。 显示英文摘要

Accreting supermassive black holes (SMBHs) in galaxy mergers with separations $<$ 1kpc are crucial to our understanding of SMBH growth, galaxy evolution, and the evolution of SMBH binaries. Despite their importance, there are less than a handful known, and most have been discovered serendipitously. In this work, we employ a new selection method to systematically pre-select candidate advanced mergers likely to contain unresolved substructure at sub-arcsecond scales. By exploiting the large survey area and astrometric precision of the Wide-field Infrared Survey Explorer (WISE) and the Sloan Digital Sky Survey (SDSS), we have identified a sample of 48 nearby advanced mergers that have red WISE colors ($W_1-W_2>0.5$) indicative of accretion activity and significant sub-arcsecond offsets between their optical and infrared coordinates as measured by SDSS and WISE. We conducted high resolution adaptive optics (AO) observations of this sample with the Keck NIRC2 camera in the $K_p$ band ($2.124 ~ \mu m$, $\Delta\lambda = 0.351 \mu m$) to search for evidence of previously unresolved substructure suggested by the optical-to-infared offsets. We find that a significant fraction (20/48 or 42%) of the sample shows substructure tracing the SDSS/WISE offset and unresolved by SDSS, demonstrating that our methodology is a promising pathway to find dual AGN in follow-up spectroscopy. Archival optical Hubble Space Telescope (HST) imaging reveals that substructure identified with Keck is often missed in the optical or erroneously identified due to partial obscuration, underscoring the importance of carrying out studies of late-stage mergers in the infrared.

交叉提交 (展示 23 之 23 条目 )

[43] arXiv:2507.03074 (交叉列表自 astro-ph.CO) [中文pdf, pdf, html, 其他]

标题： 可微分的晕质量预测以及晕质量函数的宇宙学依赖性 显示英文标题

标题： Differentiable Halo Mass Prediction and the Cosmology-Dependence of Halo Mass Functions

Jim Buisman, Florian List, Oliver Hahn

评论： 13 + 4页，11 + 3图，将提交至OJA，欢迎提出意见

主题： 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA)

现代宇宙学推断越来越依赖可微分模型，以实现高效的基于梯度的参数估计和不确定性量化。 在这里，我们提出了一种新的方法，使用可微分的场级神经网络（NN）模型来预测暗物质晕的丰度及其对宇宙学参数的依赖性，并研究常见的晕质量函数（HMF）参数化方式以及我们的NN方法在多大程度上捕捉到这种依赖性。 通过在不同宇宙学参数的快速N体模拟的初始密度场上训练3D U-Net，我们实现了从线性密度场到原晕区域及其质量区间的直接、可微分映射。 我们的方法在识别原晕区域以及捕捉HMF对宇宙学参数的依赖性方面表现出具有竞争力的准确性。 我们的NN导数与分析和模拟的HMF的有限差分结果在不同模型之间的差异水平上高度一致。 我们进一步展示了NN模型如何还可用于研究HMF对初始高斯随机场变化的响应。 最后，我们还证明了可微分模型可以用于在极高精度下外推现有模型。 显示英文摘要

Modern cosmological inference increasingly relies on differentiable models to enable efficient, gradient-based parameter estimation and uncertainty quantification. Here, we present a novel approach for predicting the abundance of dark matter haloes and their cosmology dependence using a differentiable, field-level neural network (NN) model, and study how well the cosmology dependence is captured by common parametrisations of the halo mass function (HMF), and by our NN-based approach. By training a 3D U-Net on initial density fields from fast N-body simulations with varying cosmological parameters, we enable direct, differentiable mapping from the linear density field to protohalo patches and their mass bins. Our method achieves competitive accuracy in identifying protohalo regions and in capturing the dependence of the HMF on cosmological parameters. Our NN derivatives agree well with finite differences of both analytical and emulated HMFs, at the level of the disagreement among the different models. We further demonstrate how the NN model can additionally be used to investigate the response of the HMF to changes in the initial Gaussian random field. Finally, we also demonstrate that a differentiable model can be used to extrapolate existing models at very high precision.

[44] arXiv:2507.03085 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]

标题： 通过多维光度函数的测量探索活动星系核的X射线-射电联系 显示英文标题

标题： Exploring the X-ray--radio connection for AGN via measurements of the multi-dimensional luminosity function

Clara M. Pennock, James Aird, Cassandra L. Barlow-Hall

评论： 提交至MNRAS

主题： 高能天体物理现象 (astro-ph.HE) ; 星系的天体物理学 (astro-ph.GA)

我们提出了新的方法，以多维光度函数来量化活动星系核（AGN）群体，该光度函数描述了源的空间密度作为X射线和射电光度的函数。 我们从Boötes和COSMOS区域编译了一个包含1891个河外射电和X射线探测源的样本。 首先，我们研究了样本中的X射线-射电光度相关性，并发现由于调查的灵敏度限制，引入了明显的相关性；在考虑单个红移区间时，我们发现给定的X射线光度与广泛的射电光度相关，反之亦然，表明发射过程之间几乎没有直接联系。 然后，我们在红移（$0<z<6$）范围内测量了X射线光度函数、射电光度函数以及多维X射线-射电光度函数。 我们在X射线和射电中应用光度阈值，将我们的样本限制在AGN主导的区域，并探讨在整体X射线样本中，射电选择的AGN的比例如何随着X射线光度的增加（反之亦然）而变化。 我们发现，在最高X射线和射电光度下，同时具有X射线和射电探测的源的比例趋于100%，这表明在最高光度下，我们更有可能在两个波段都获得探测，尽管源不一定在两个波段都明亮。 因此，最明亮的吸积事件更可能与喷流的产生有关，尽管产生辐射的物理结构不同，并且可能在非常不同的时间尺度上持续。 显示英文摘要

We present new methods to quantify the AGN population in terms of a multi-dimensional luminosity function that describes the space density of sources as a function of both X-ray and radio luminosity. We compile a sample of 1891 radio and X-ray detected extragalactic sources from the Bo\"otes and COSMOS fields. First, we investigate the X-ray--radio luminosity correlation in the sample and find that an apparent correlation is introduced due to the sensitivity limits of the surveys; when considering individual redshift bins we find a wide range of radio luminosities associated with a given X-ray luminosity, and vice versa, indicating little direct connection between the emission processes. We then measure the X-ray luminosity function, radio luminosity function and multi-dimensional X-ray--radio luminosity function across redshift ($0<z<6$). We apply luminosity thresholds in X-ray and radio to restrict our sample to those in the AGN-dominated regime and explore how the fraction of radio-selected AGN within the overall X-ray sample varies with increasing X-ray luminosity (and vice versa). We find that towards the highest X-ray and radio luminosities the fraction of sources with both an X-ray and radio detection increases towards 100%, indicating that at the highest luminosities we are more likely to obtain a detection in both bands, though the source will not necessarily be bright in both bands. Thus, the most luminous accretion events are more likely to be associated with the production of a jet, despite the distinct physical structures that produce the emission and likely persist over very different timescales.

[45] arXiv:2507.03088 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]

标题： 朝向耀变体演化的统一方案 显示英文标题

标题： Towards a unified scheme of blazar evolution

E. Oukacha, Y. Becherini

主题： 高能天体物理现象 (astro-ph.HE) ; 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA)

机器学习（ML）和深度学习（DL）技术在天体物理学中被越来越广泛地使用，这得益于数据的日益丰富和获取方法的改进。 这些方法现在支持从红移估计到源分类的各种任务。 在本工作中，我们的目标是（i）对费米4LAC-DR3目录中的耀变体进行分类，特别是识别不确定类型的耀变体（BCUs）的可能来源，并（ii）研究完整的耀变体样本，以研究它们的结构和红移-光度演化。 我们特别关注平坦谱射电类星体（FSRQs）和BL拉科特天体（BL Lacs）之间的过渡区域，这可能为吸积盘演化提供见解。 我们考察变化外观耀变体（CLBs）作为这一过渡过程中的潜在中间体。 我们采用了一个分类流程，同时使用了一个强大的基准模型（XGBoost）和一个在数百万个表格数据集上预训练的基础模型（TabPFN）。 通过提取和降低最佳模型的高维潜在空间，我们提供了耀变体种群的二维表示。 这揭示了FSRQs和BL Lacs之间的连续性，包括CLBs作为过渡源。 这些结果支持了一种从辐射有效（类似FSRQ）到无效（类似BL Lac）吸积的渐进演化场景。 最终，我们表明，一个单一的概率分数结合潜在空间，提供了一个超越离散类别的新框架来解释耀变体的多样性。 显示英文摘要

Machine learning (ML) and deep learning (DL) techniques are increasingly used across astrophysics, enabled by the growing availability of data and improved acquisition methods. These approaches now support tasks from redshift estimation to source classification. In this work, we aim to (i) classify blazars from the Fermi 4LAC-DR3 catalogue, in particular to identify the likely origin of blazars of uncertain type (BCUs), and (ii) investigate the full blazar sample to study their structure and redshift-luminosity evolution. We focus especially on the transition region between Flat Spectrum Radio Quasars (FSRQs) and BL Lacertae objects (BL Lacs), which may yield insights into accretion disk evolution. We examine Changing-Look Blazars (CLBs) as potential intermediates in this transition. We implement a classification pipeline using both a strong benchmark model (XGBoost) and a foundation model pre-trained on millions of tabular datasets (TabPFN). By extracting and reducing the high-dimensional latent space of the best model, we provide a 2D representation of the blazar population. This reveals a continuum between FSRQs and BL Lacs, including CLBs as transitional sources. These results support a scenario of gradual evolution from radiatively efficient (FSRQ-like) to inefficient (BL Lac-like) accretion. Ultimately, we show that a single probability score, combined with the latent space, offers a new framework for interpreting blazar diversity beyond discrete classes.

[46] arXiv:2507.03105 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]

标题： 射电形态的伽马射线源 -- 第二部分。 巨型射电星系 显示英文标题

标题： Radio Morphology of Gamma-ray Sources -- II. Giant Radio Galaxies

Vaidehi S. Paliya, D. J. Saikia, Gabriele Bruni, Alberto Dominguez, C. S. Stalin

评论： 天体物理杂志，待发表

主题： 高能天体物理现象 (astro-ph.HE) ; 星系的天体物理学 (astro-ph.GA)

巨射电源，包括星系和类星体（以下简称GRGs），是拥有相对论喷流的活动星系核（AGN），其源尺寸超过0.7 Mpc的投影长度。 它们对于理解射电源的演化及其与周围环境的相互作用至关重要。 其中一些神秘的天体，例如NGC 315，也被报道为伽马射线发射体。 由于GRGs被认为接近天球平面，因此它们是探索导致观测到的伽马射线辐射的辐射机制的重要目标。 我们利用灵敏的低分辨率射电调查，如低频阵列、国家射电天文台VLA天空调查和快速ASKAP连续谱调查，对伽马射线发射的GRGs进行了系统搜索，并考虑了第四次数据发布第四次费米大面积望远镜伽马射线源（4FGL-DR4）目录。 通过仔细检查4FGL-DR4目录中所有AGN的射电图，我们识别出16个伽马射线发射的GRGs，其中8个是首次被报告为GRGs。 它们的一些观测参数，例如核心主导性，似乎与未被伽马射线探测到的GRG群体不同，这可能是由于伽马射线发射喷流的相对较小的观测角度。 这些天体的观测伽马射线特性与非GRG伽马射线发射的错位AGN相似。 我们得出结论，这两个源群体中的伽马射线发射起源可能是相似的。 显示英文摘要

Giant radio sources, including galaxies and quasars (hereafter GRGs), are active galactic nuclei (AGN) hosting relativistic jets with source sizes exceeding the projected length of 0.7 Mpc. They are crucial to understanding the evolution of radio sources and their interaction with the surrounding environment. Some of these enigmatic objects, e.g., NGC 315, have also been reported as gamma-ray emitters. Since GRGs are thought to be aligned close to the plane of the sky, they are invaluable targets to explore the radiative mechanisms responsible for the observed gamma-ray emission. We have carried out a systematic search of gamma-ray emitting GRGs using sensitive low-resolution radio surveys, such as by Low Frequency Array, NRAO VLA Sky Survey, and Rapid ASKAP Continuum Survey, and considering the fourth data release of the fourth Fermi-Large Area Telescope gamma-ray source (4FGL-DR4) catalog. By carefully inspecting the radio maps of all AGN included in the 4FGL-DR4 catalog, we have identified 16 gamma-ray emitting GRGs, including 8 of them being reported as GRGs for the first time. Some of their observed parameters, e.g., core dominance, appeared to differ from that found for the non-gamma-ray detected GRG population, possibly due to the relatively small viewing angle of the gamma-ray emitting jet. The observed gamma-ray properties of these objects were found to be similar to non-GRG gamma-ray emitting misaligned AGN. We conclude that the origin of the gamma-ray emission could be similar in both source populations.

[47] arXiv:2507.03180 (交叉列表自 astro-ph.IM) [中文pdf, pdf, html, 其他]

标题： 宜居世界天文台：天体物理r过程的性质 显示英文标题

标题： Habitable Worlds Observatory: The Nature of the Astrophysical r-process

Ian U. Roederer, Rana Ezzeddine

评论： 5页（提交给ASP会议的HWO2025科学案例开发文件）

主题： 天体物理学的仪器与方法 (astro-ph.IM) ; 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

我们提出对周期表中最重元素起源的科学案例，重点是利用宜居世界观测站（HWO）研究通过快速中子捕获过程（r-过程）产生的元素。 高分辨率紫外（UV）光谱学可以将可检测到的r-过程元素数量相对于光学和红外光谱增加50%以上。 这些元素对于表征控制r-过程的物理条件以及确定r-过程事件发生的性质、地点和环境至关重要。 HWO有潜力大幅扩展在太阳邻域以外的银河晕、球状星团和矮星系中可以检测到罕见研究的重元素的恒星样本。 显示英文摘要

We present the science case for characterizing the origin of the heaviest elements on the periodic table, with a focus on those produced by the rapid neutron-capture process (r-process), using the Habitable Worlds Observatory (HWO). High-resolution ultraviolet (UV) spectroscopy can increase the number of r-process elements detectable in cool stars by more than 50% relative to optical and infrared spectra. These elements are key to characterizing the physical conditions that govern the r-process and identify the nature, sites, and environments where r-process events occurred. HWO has the potential to greatly expand the sample of stars where rarely studied heavy elements can be detected beyond the Solar neighborhood to the Galactic halo, globular clusters, and dwarf galaxies.

[48] arXiv:2507.03181 (交叉列表自 astro-ph.IM) [中文pdf, pdf, html, 其他]

标题： 宜居世界天文台：第一颗恒星的性质 显示英文标题

标题： Habitable Worlds Observatory: The Nature of the First Stars

Ian U. Roederer, Rana Ezzeddine, Jennifer S. Sobeck

评论： 5页（提交给ASP会议的HWO2025会议科学案例开发文件）

主题： 天体物理学的仪器与方法 (astro-ph.IM) ; 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

我们提出利用宜居世界观测站（HWO）来表征第一颗恒星本质的科学案例。 使用HWO进行高分辨率紫外（UV）光谱分析，有望通过将它们的金属丰度限制在前所未有的低水平来确认任何幸存的低质量零金属第一颗恒星。 它还有潜力显著增加在已知长寿命低质量恒星光谱中可检测到的元素数量，这些恒星表现出极低的金属丰度，揭示了第一颗恒星产生的金属。 对于这一科学案例具有重要价值且具有紫外跃迁的元素包括碳、镁、铝、硅、磷、硫、钪、钒、铬、锰、铁、钴、镍、铜和锌。 与哈勃空间望远镜相比，HWO将扩大发现范围，因为它能够对银河系及邻近恒星系统中更暗淡的恒星进行高分辨率紫外光谱分析。 显示英文摘要

We present the science case for characterizing the nature of the first stars using the Habitable Worlds Observatory (HWO). High-resolution ultraviolet (UV) spectroscopy with the HWO has the potential to confirm any surviving low-mass zero-metallicity first stars by placing unprecedented low limits on their metal abundances. It also has the potential to substantially increase the number of elements detectable in the spectra of known long-lived low-mass stars, which exhibit extremely low metal abundances that reveal the metals produced by the first stars. Elements important for this science case with UV transitions include C, Mg, Al, Si, P, S, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn. HWO would expand the discovery space when compared with the Hubble Space Telescope by enabling high-resolution UV spectroscopy for much fainter stars throughout the Milky Way and neighboring stellar systems.

[49] arXiv:2507.03371 (交叉列表自 astro-ph.IM) [中文pdf, pdf, html, 其他]

标题： 非常大质量恒星与宜居世界观测站 显示英文标题

标题： Very Massive Stars with the Habitable Worlds Observatory

Fabrice Martins (1), Aida Wofford (2), Miriam Garcia (3), Peter Senchyna (4), Janice Lee (5,6), Paul A. Scowen (7) ((1) CNRS, Univ. Montpellier, (2), UNAM, (3) CSIC-INTA, (4) Carnegie Institution for Science, (5) STScI, (6) University of Arizona, (7) NASA/GSFC)

评论： 9页，4图。HWO科学案例，将在会议“迈向宜居世界观测站：远见科学与变革性技术”上发表，并提交给太平洋天文学会

主题： 天体物理学的仪器与方法 (astro-ph.IM) ; 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

非常大质量恒星（VMS）被定义为初始质量超过100 Msun 的恒星。 由于它们的寿命很短以及恒星质量函数的形状，它们是稀有天体。 在银河系和大麦哲伦星云中仅已知约二十个。 然而VMS在多个方面都很重要。 它们通过增强的恒星风有效地传播核合成产物，它们被预测会以对不稳定超新星爆炸或从直接坍缩形成大质量黑洞，而且它们在紫外线中比所有其他类型的恒星更明亮，因此主导了星暴的综合光。 它们的存在在所有红移范围内都被间接怀疑，一直到宇宙黎明时期，那时它们可能在第一个星系的形成中发挥了关键作用。 目前，由于仪器限制，尤其是空间分辨率，它们的搜索和识别受到阻碍。 一个在HWO（5mas）衍射极限下工作的积分场光谱仪，具有约2000的光谱分辨率，将彻底改变对VMS的理解。 在本文中，我们提出了这种仪器的必要性。 显示英文摘要

Very massive stars (VMS) are defined as stars with an initial mass in excess of 100 Msun. Because of their short lifetime and the shape of the stellar mass function, they are rare objects. Only about twenty of them are known in the Galaxy and the Large Magellanic Cloud. However VMS are important in several ways. They efficiently spread nucleosynthesis products through their boosted stellar winds, they are predicted to explode as pair-instability supernovae or to form heavy black-holes from direct collapse, and they outshine all other types of stars in the ultraviolet light, thus dominating the integrated light of starbursts. Their presence is indirectly suspected across all redshifts, all the way to cosmic dawn where they may have played a key role in the formation of the first galaxies. Their search and identification is currently hampered by instrumental limitation, especially spatial resolution. An integral field spectrograph working at the diffraction limit of HWO (5mas) and with a spectral resolution of about 2000 would revolutionize the understanding of VMS. We make the case for such an instrument in this contribution.

[50] arXiv:2507.03412 (交叉列表自 astro-ph.CO) [中文pdf, pdf, html, 其他]

标题： SKYSURF IX -- 从综合星系光测量得到的宇宙光学和红外背景 显示英文标题

标题： SKYSURF IX -- The Cosmic Optical and Infrared Background from Integrated Galaxy Light Measurements

Scott A. Tompkins, Simon P. Driver, Aaron S. G. Robotham, Rogier A. Windhorst, Delondrae Carter, Timothy Carleton, Zak Goisman, Daniel Henningsen, Luke J. Davies, Sabine Bellstedt, Jordan C. J. D'Silva, Juno Li, Seth H. Cohen, Rolf A. Jansen, Rosalia O'Brien, Anton M. Koekemoer, Norman Grogin, John MacKenty

评论： 34页

主题： 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA)

作为SKYSURF哈勃空间望远镜（HST）遗产档案计划的一部分，我们提供了星系数量计数，这些计数在15个不同波长上给出了河外背景光（EBL）的测量值。 我们使用相同的软件和处理流程，将23个滤镜下的82,752张HST图像处理成16,686幅马赛克。 利用提供可靠星系计数的17/23个滤镜，我们在0.3至1.6$\mu$m范围内结合WAVES（广域VISTA河外调查）和DEVILS（深河外可见遗产调查）的8个波段，对综合星系光（IGL）进行了1.5-9%误差范围内的约束。 虽然HST从未旨在进行大范围的巡天，但通过广泛的质量控制和过滤，我们能够提取出一个可靠且具有代表性的场样本，这些场分布在天空的不同位置。 我们的最终目录覆盖了总共$\approx 19.6 \deg^2$，其中每个滤镜覆盖的区域范围从$\approx 0.16-7.0 \deg^2$。 众多独立视线和面积覆盖的结合使我们能够将深度数量计数中的宇宙方差不确定性降低到0.06%-1.8%。 首次我们能够利用HST数据在0.59$\mu$m处建立对IGL，$\mathrm{9.07 \pm 0.35 nW m^{-2} sr^{-1}}$的测量。 我们获得了一个宇宙光学背景值为$ 24.45 \pm 0.50 \mathrm{nW m^{-2} sr^{-1}}$。 用于测量COB的各种技术，无论是直接还是间接，最近都趋于一致，表明COB几乎完全来自星系内部的过程。 这与来自新地平线（New Horizons）的最新值以及极高能（VHE）约束相结合，使得银河系以外任何弥散辐射的存在空间非常有限。 显示英文摘要

As part of the SKYSURF Hubble Space Telescope (HST) Legacy Archival program we present galaxy number counts which yield measurements of the extragalactic background light (EBL) at 15 different wavelengths. We have processed 82,752 HST images across 23 filters into 16,686 mosaics using the same software and processing pipeline throughout. Using 17/23 filters that give reliable galaxy counts, we constrain the integrated galaxy light (IGL) with a 1.5-9\% error between 0.3 and 1.6 $\mu$m in combination with 8 bands from WAVES (Wide Area VISTA Extragalactic Survey) and DEVILS (Deep Extragalactic Visible Legacy Survey). While HST was never intended to undertake large area surveys, through extensive quality control and filtering, we were able to extract a reliable and representative sample of fields distributed across the sky. Our final catalogs cover a combined $\approx 19.6 \deg^2$, with individual filters covering areas ranging from $\approx 0.16-7.0 \deg^2$. The combination of numerous independent sight-lines and area coverage allows us to reduce cosmic variance uncertainties in deep number counts to 0.06\%-1.8\%. For the first time we are able to establish a measurement of the IGL, $\mathrm{9.07 \pm 0.35 nW m^{-2} sr^{-1}}$, at 0.59 $\mu$m using HST data. We obtain a cosmic optical background value of $ 24.45 \pm 0.50 \mathrm{nW m^{-2} sr^{-1}}$. Different techniques used to measure the COB, both directly and indirectly, have recently converged indicating that the COB arises almost exclusively from processes within galaxies. This in combination with the recent values reported from New Horizons and very high energy (VHE) constraints leaves very little room for any diffuse emission coming from outside the Milky Way.

[51] arXiv:2507.03613 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]

标题： 候选中微子发射耀变体的物理性质 显示英文标题

标题： The physical properties of candidate neutrino-emitter blazars

Alessandra Azzollini, Sara Buson, Alexis Coleiro, Gaëtan Fichet de Clairfontaine, Leonard Pfeiffer, Jose Maria Sanchez Zaballa, Margot Boughelilba, Massimiliano Lincetto

评论： 22页，8张图，已接受发表于《天文学与天体物理学》

主题： 高能天体物理现象 (astro-ph.HE) ; 星系的天体物理学 (astro-ph.GA)

天体物理高能中微子的产生过程仍在争论之中，其来源仍然是一个开放性问题。 在可能的发射源中，活动星系核引起了越来越多的关注。 特别是耀变体，由于它们能够在存在外部辐射场的环境中加速粒子而脱颖而出。 最近的观测表明，它们可能对IceCube探测到的中微子通量有所贡献。 我们研究了52个被提议作为候选中微子发射体的耀变体子样本的物理特性，这是基于IceCube热点与5BZCat目录之间的位置交叉相关分析。 我们的目标是首次对它们的中心引擎和物理性质进行表征，以探索与中微子产生的潜在联系。 我们分析了这52个候选中微子发射体耀变体的光学光谱特性，以推断它们的吸积模式。 该研究还补充了射电和$\gamma$-射线数据，这些数据追踪了喷流的固有功率。 我们将样本与其他文献中的耀变体群体进行比较，进行统计检验，并通过模拟探讨包含截断数据的方法的适用性。 总体而言，目标样本的特性与参考样本相容。 我们观察到一种轻微的倾向，即更倾向于具有强辐射场的物体，这通常是辐射效率高的吸积体的特征，以及高射电功率。 其中，24个被Fermi-LAT检测到，涵盖了各种$\gamma$-射线光度。 我们还表明，文献中常用的统计检验需要谨慎处理，因为它们对截断数据的数量和样本大小敏感。 显示英文摘要

The processes governing the production of astrophysical high-energy neutrinos are still debated, and the sources originating them remain an open question. Among the putative emitters, active galactic nuclei have gained increasing attention. Blazars, in particular, stand out due to their ability to accelerate particles in environments with external radiation fields. Recent observations suggest they may contribute to the neutrino flux detected by IceCube. We study the physical properties of a subsample of 52 blazars proposed as candidate neutrino emitters, based on a positional cross-correlation analysis between IceCube hotspots and the 5BZCat catalog. We aim to provide a first characterization of their central engines and physical nature, to explore the potential link with neutrino production. We analyze the optical spectroscopic properties of the 52 candidate neutrino-emitter blazars to infer their accretion regime. The study is complemented by radio and $\gamma$-ray data, which trace the intrinsic jet power. We compare the sample to other blazar populations in the literature, perform statistical tests, and explore, through simulations, the applicability of methods that include censored data. Overall, the target sample shows properties compatible with the reference samples. We observe a mild tendency to prefer objects with intense radiation fields, typical of radiatively efficient accretors, and high radio power. Among them, 24 are detected by Fermi-LAT, spanning various $\gamma$-ray luminosities. We also show that statistical tests commonly used in the literature need to be handled with caution, as they are sensitive to the number of censored data and the sample size.

[52] arXiv:2507.03778 (交叉列表自 gr-qc) [中文pdf, pdf, html, 其他]

标题： 贝肯斯坦-霍金熵：简要概述 显示英文标题

标题： Bekenstein-Hawking Entropy: A Brief Overview

Ricardo Bulcão Valente Ferrari, Samuel Bueno Soltau

主题： 广义相对论与量子宇宙学 (gr-qc) ; 星系的天体物理学 (astro-ph.GA)

在20世纪70年代初，雅各布·贝肯斯坦提出黑洞具有与其事件视界面积成比例的熵，引入了热力学广义第二定律。史蒂芬·霍金最初反对这一观点，但随后他对弯曲时空中的量子场论的分析导致了霍金辐射和黑洞温度概念的预测。这项研究简要概述了1972年至1975年间黑洞热力学的发展，强调了贝肯斯坦和霍金贡献的理论演变。这项工作还反思了这些发展对现代理论物理和量子引力的持久影响。 显示英文摘要

In the early 1970s, Jacob Bekenstein proposed that black holes possess an entropy proportional to the area of their event horizon, introducing the Generalized Second Law of thermodynamics. Stephen Hawking initially objected to this idea, but his subsequent analysis of quantum field theory in curved spacetime led to the prediction of Hawking radiation and the concept of black hole temperature. This study offers a concise overview of the development of black hole thermodynamics between 1972 and 1975, highlighting the theoretical evolution of both Bekenstein's and Hawking's contributions. The work also reflects on the lasting impact of these developments on modern theoretical physics and quantum gravity.

[53] arXiv:2507.03857 (交叉列表自 gr-qc) [中文pdf, pdf, html, 其他]

标题： 明亮环状特征和极化结构在由辐射低效吸积流照亮的Kerr-Sen黑洞图像中 显示英文标题

标题： Bright ring features and polarization structures in Kerr-Sen black hole images illuminated by radiatively inefficient accretion flows

Hao Yin, Songbai Chen, Jiliang Jing

评论： 16页，9图

主题： 广义相对论与量子宇宙学 (gr-qc) ; 星系的天体物理学 (astro-ph.GA) ; 高能天体物理现象 (astro-ph.HE)

我们基于广义相对论辐射转移（GRRT）模拟，研究了克尔-森黑洞图像中的明亮环状特征和偏振结构，这些结构由辐射效率低的吸积流（RIAF）在230 GHz处的热同步辐射发射照亮。 使用REx方法，我们从黑洞图像中提取了明亮环，并发现随着膨胀参数的增加，明亮环和黑洞阴影都会缩小。 结合事件视界望远镜（EHT）对SgrA*的观测数据，我们给出了不同观测倾角和盘厚度下黑洞参数的允许范围。 我们的结果表明，盘厚度对允许参数空间的影响比观测倾角的影响更强。 我们通过分析系数$\beta_2$探究了黑洞图像偏振结构中EVPA的旋转对称性。 稀释参数导致实部$Re\beta_2$增加，虚部$Im\beta_2$减少，但幅度$|\beta_2|$通常呈现下降趋势。 最后，我们发现盘厚度对$\beta_2$的影响远弱于稀释参数的影响。 显示英文摘要

We have investigated the bright ring-like features and polarization structures in the Kerr-Sen black hole's images based on general relativistic radiative transfer (GRRT) simulations, which are illuminated by the 230 GHz thermal synchrotron emission from the radiatively inefficient accretion flows (RIAF). Using the REx method, we extracted the bright ring from the black hole images and found that both the bright ring and black hole shadow shrink as the dilation parameter increases. Combing with the Event Horizon Telescope (EHT) observational data of SgrA*, we present the allowed ranges of black hole parameters for different observed inclinations and disk thicknesses. Our results show that effects of the disk thickness on the allowed parameter space are more strong than those of the observed inclination. We also probe the rotational symmetry of EVPA in the polarization structure of the black hole images by analyzing the coefficient $\beta_2$. The dilaton parameter results in that the real part $Re\beta_2$ increases and the imaginary part $Im\beta_2$ decreases, but the magnitude $|\beta_2|$ generally exhibits a declining trend. Finally, we find that effects of the disk thickness on $\beta_2$ are much weaker than those from the dilaton parameter.

[54] arXiv:2507.03970 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]

标题： 搜索星系合并与费米-LAT 4FGL-DR4源的空间重合 显示英文标题

标题： Search for spatial coincidences between galaxy mergers and Fermi-LAT 4FGL-DR4 sources

Siddhant Manna, Shantanu Desai

评论： 7页，2图

主题： 高能天体物理现象 (astro-ph.HE) ; 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA)

我们系统地搜索了通过SDSS成像检测到的3,166个高置信度形态选择的星系合并与费米大面积望远镜（LAT）检测到的4FGL-DR4伽马射线源目录之间的空间关联。 使用保守的4$\sigma$位置不确定性阈值和基于泊松统计框架，我们识别出21个统计显著的关联，匹配概率为$p < 0.05$。 其中包含已知的伽马射线发射体类别，如平坦谱射电类星体（FSRQs）、BL拉科特天体（BLL）和射电星系，支持了由合并驱动的过程可以为高能活动提供能量的假设。 有趣的是，五个相关源在4FGL-DR4中仍未分类，暗示星系合并可能与此前未被认识的伽马射线源群体有关。 AGN-like匹配的主导地位支持了这样的情景：合并触发了中心超大质量黑洞的吸积，引发了可在伽马射线能量下观测到的AGN活动。 此外，未关联源在可靠匹配中的反复出现强调了合并目录在伽马射线源识别工作中的物理动机先验的潜力。 这项工作是首次专门努力探索伽马射线源与大规模形态选择的星系合并样本之间的关联，为理解相互作用在高能天体物理学中的作用开辟了新途径。 我们还检查了来自加拿大网络观测宇宙学领域星系红移巡天的70对星系样本，未发现统计显著的匹配，$p < 0.05$在4$\sigma$的位置不确定性阈值内。 显示英文摘要

We present a systematic search for spatial association between a high-confidence sample of 3,166 morphologically selected galaxy mergers detected through SDSS imaging and the 4FGL-DR4 catalog of gamma-ray sources detected by the Fermi Large Area Telescope (LAT). Using a conservative 4$\sigma$ positional uncertainty threshold and a Poisson-based statistical framework, we identify 21 statistically significant associations with match probabilities $p < 0.05$. Among these are known classes of gamma-ray emitters such as flat-spectrum radio quasars (FSRQs), BL Lacertae objects (BLL), and radio galaxies bolstering the hypothesis that merger-driven processes can fuel high-energy activity. Intriguingly, five of the associated sources remain unclassified in 4FGL-DR4, hinting at a possible link between galaxy mergers and a hitherto unrecognized population of gamma-ray sources. The dominance of AGN-like matches supports the scenario in which mergers trigger accretion onto central supermassive black holes, initiating AGN activity observable at gamma-ray energies. Moreover, the recurrent presence of unassociated sources among secure matches underscores the potential of merger catalogs as physically motivated priors in gamma-ray source identification efforts. This work constitutes the first dedicated effort to explore associations between gamma-ray sources and a large, morphologically selected sample of galaxy mergers, opening new avenues for understanding the role of interactions in high-energy astrophysics. We additionally examined the sample of 70 galaxy pairs from the Canadian Network for Observational Cosmology Field Galaxy Redshift Survey and found no statistically significant matches, with $p < 0.05$ within the 4$\sigma$ positional uncertainty threshold.

[55] arXiv:2507.03989 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]

标题： 寻找毫米波明亮的耀变体作为天体中微子源 显示英文标题

标题： A Search for Millimeter-Bright Blazars as Astrophysical Neutrino Sources

R. Abbasi, M. Ackermann, J. Adams, S. K. Agarwalla, J. A. Aguilar, M. Ahlers, J.M. Alameddine, N. M. Amin, K. Andeen, C. Argüelles, Y. Ashida, S. Athanasiadou, S. N. Axani, R. Babu, X. Bai, J. Baines-Holmes, A. Balagopal V., S. W. Barwick, S. Bash, V. Basu, R. Bay, J. J. Beatty, J. Becker Tjus, P. Behrens, J. Beise, C. Bellenghi, B. Benkel, S. BenZvi, D. Berley, E. Bernardini, D. Z. Besson, E. Blaufuss, L. Bloom, S. Blot, I. Bodo, F. Bontempo, J. Y. Book Motzkin, C. Boscolo Meneguolo, S. Böser, O. Botner, J. Böttcher, J. Braun, B. Brinson, Z. Brisson-Tsavoussis, R. T. Burley, D. Butterfield, M. A. Campana, K. Carloni, J. Carpio, S. Chattopadhyay, N. Chau, Z. Chen, D. Chirkin, S. Choi, B. A. Clark, A. Coleman, P. Coleman, G. H. Collin, A. Connolly, J. M. Conrad, R. Corley, D. F. Cowen, C. De Clercq, J. J. DeLaunay, D. Delgado, T. Delmeulle, S. Deng, P. Desiati, K. D. de Vries, G. de Wasseige, T. DeYoung, J. C. Díaz-Vélez, S. DiKerby, M. Dittmer, A. Domi, L. Draper, L. Dueser, D. Durnford, K. Dutta, M. A. DuVernois, T. Ehrhardt, L. Eidenschink, A. Eimer, P. Eller, E. Ellinger, D. Elsässer, R. Engel, H. Erpenbeck, W. Esmail, S. Eulig, J. Evans, P. A. Evenson, K. L. Fan, K. Fang, K. Farrag, A. R. Fazely, A. Fedynitch, N. Feigl, C. Finley, L. Fischer

评论： 24页，8张图。已提交至天体物理期刊

主题： 高能天体物理现象 (astro-ph.HE) ; 星系的天体物理学 (astro-ph.GA)

类星体的强大喷流历来被认为可能是高能宇宙射线加速的可能场所。 然而，喷流的详细情况以及轻子和强子喷流加载的位置仍然不清楚。 当轻子和强子粒子注入同时发生时，预期会存在同步辐射和中微子产生之间的时间相关性。 我们使用来自阿塔卡马宇宙学望远镜的毫米（mm）波长类星体光变曲线的第一个目录，与冰立方南级中微子天文台十二年的μ子中微子事件进行时间相关的分析。 这种毫米辐射已知可以追踪明亮喷流基部的活动，这在较低频率下通常会被自吸收，并且可能对伽马射线不透明。 我们对群体进行了分析，以及对个别选定源的分析。 我们没有从堆叠群体中观察到显著信号。 TXS 0506+056被发现是最重要的单个源，尽管在我们对选定活动星系核的分析中，这一检测并不具有全局显著性。 我们的结果表明，大多数毫米波亮类星体是中微子暗的。 一般来说，许多类星体可能有较轻的、以轻子为主的喷流，或者只有选定的类星体提供中微子产生的特殊条件。 显示英文摘要

The powerful jets of blazars have been historically considered as likely sites of high-energy cosmic-ray acceleration. However, particulars of the launched jet and the locations of leptonic and hadronic jet loading remain unclear. In the case when leptonic and hadronic particle injection occur jointly, a temporal correlation between synchrotron radiation and neutrino production is expected. We use a first catalog of millimeter (mm) wavelength blazar light curves from the Atacama Cosmology Telescope for a time-dependent correlation with twelve years of muon neutrino events from the IceCube South Pole Neutrino Observatory. Such mm emission is known to trace activity of the bright jet base, which is often self-absorbed at lower frequencies and potentially gamma-ray opaque. We perform an analysis of the population, as well as analyses of individual, selected sources. We do not observe a significant signal from the stacked population. TXS 0506+056 is found as the most significant, individual source, though this detection is not globally significant in our analysis of selected AGN. Our results suggest that the majority of mm-bright blazars are neutrino dim. In general, it is possible that many blazars have lighter, leptonic jets, or that only selected blazars provide exceptional conditions for neutrino production.

[56] arXiv:2507.04280 (交叉列表自 gr-qc) [中文pdf, pdf, html, 其他]

标题： 近日点进动在Zipoy-Voorhees时空中的情况 显示英文标题

标题： Periapsis shift in the Zipoy-Voorhees spacetime

Akihito Katsumata, Tomohiro Harada

评论： 38页，7图

主题： 广义相对论与量子宇宙学 (gr-qc) ; 星系的天体物理学 (astro-ph.GA)

我们研究了Zipoy-Voorhees时空中类时束缚轨道的近日点进动，该时空是一个由变形参数$\gamma$表征的精确、静态、轴对称且真空解，包括Schwarzschild时空作为$\gamma=1$。 我们推导了准圆轨道的近日点进动的精确公式以及通过后牛顿（PN）展开的近日点进动公式。 我们表明，在Zipoy-Voorhees时空中，当$e=\sqrt{(\gamma^{-1}-5)/6}$时，对于$1/11 < \gamma \leq 1/5$，近日点进动在2PN阶与Schwarzschild时空相同，其中$e$是轨道的偏心率。 此外，我们表明，人马座A*处的超大质量致密天体的参数$\gamma$和相应的四极矩$\tilde{M}_2$分别被观测数据对S2的观测结果限制为$\gamma \gtrsim 1.7 \times 10^{-2}$和$\tilde{M}_2 \lesssim 1.2 \times 10^3$，这是通过获得的PN展开公式得到的。最后，我们使用一种最近提出的方案，得到了Zipoy-Voorhees时空中近日点进动的新级数表示，该表示不仅在弱场区域收敛迅速，而且对于小偏心率也表现出快速收敛。 显示英文摘要

We study the periapsis shift of timelike bound orbits in the Zipoy-Voorhees spacetime, which is an exact, static, axisymmetric, and vacuum solution characterized by the deformation parameter $\gamma$, including the Schwarzschild spacetime as $\gamma=1$. We derive both the exact formula for the periapsis shift of a quasi-circular orbit and the formula for the periapsis shift by the post-Newtonian (PN) expansion. We show that the periapsis shift in the Zipoy-Voorhees spacetime for $1/11 < \gamma \leq 1/5$ is the same as in the Schwarzschild spacetime to the 2PN order if $e=\sqrt{(\gamma^{-1}-5)/6}$, where $e$ is the eccentricity of the orbit. Furthermore, we show that the parameter $\gamma$ and the corresponding quadrupole moment $\tilde{M}_2$ of the supermassive compact object at Sagittarius A* are constrained to $\gamma \gtrsim 1.7 \times 10^{-2}$ and $\tilde{M}_2 \lesssim 1.2 \times 10^3$, respectively, from observational data on S2 using the obtained PN expansion formula. Finally, we derive a new series representation for the periapsis shift in the Zipoy-Voorhees spacetime using a recently proposed prescription, which shows fast convergence not only in the weak-field regime but also for small eccentricity.

[57] arXiv:2507.04389 (交叉列表自 gr-qc) [中文pdf, pdf, html, 其他]

标题： 旋转的黑洞在天体物理环境中 显示英文标题

标题： Spinning black holes in astrophysical environments

Pedro G. S. Fernandes, Vitor Cardoso

评论： 5页，2图+补充材料

主题： 广义相对论与量子宇宙学 (gr-qc) ; 星系的天体物理学 (astro-ph.GA) ; 高能天体物理现象 (astro-ph.HE) ; 高能物理 - 现象学 (hep-ph)

我们提出了一种由各向异性流体源驱动的爱因斯坦场方程的定态和轴对称黑洞解，描述了嵌入天体物理环境中的旋转黑洞。我们计算了它们的物理性质，包括与无质量及有质量粒子的圆轨道相关的量，分析了它们的阴影和图像特征以及能量条件。总体而言，我们发现偏离克尔度规的情况随着自旋的增加而增大。 显示英文摘要

We present stationary and axially-symmetric black hole solutions to the Einstein field equations sourced by an anisotropic fluid, describing rotating black holes embedded in astrophysical environments. We compute their physical properties, including quantities associated with the circular geodesics of massless and massive particles, analyze their shadows and image features, and energy conditions. Overall, we find that deviations from the Kerr metric grow with spin.

[58] arXiv:2507.04727 (交叉列表自 astro-ph.CO) [中文pdf, pdf, html, 其他]

标题： 关于XRISM对星系团介质中湍流的X射线测量的解释：与宇宙学模拟的比较 显示英文标题

标题： On the interpretation of XRISM X-ray measurements of turbulence in the intracluster medium: a comparison with cosmological simulations

F. Vazza, G. Brunetti

评论： 5页，5图，于2025年6月24日提交至A&A

主题： 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA) ; 等离子体物理 (physics.plasm-ph)

我们研究了通过XRISM在室女座星系团中利用X射线光谱学最近测量的湍流气体运动特性，是否与大尺度上由典型高分辨率宇宙学模拟产生的“经典”流体图景存在矛盾。 我们使用了一个类似室女座星系团的高分辨率模拟，并表明模拟中测量到的类似Kolmogorov的湍流能够产生与XRISM对室女座星系团观测结果完全兼容的速度结构函数和线宽。 这些结果突显了由星系团内介质中湍流的不均匀性以及观测中的X射线加权共同驱动的偏差，并似乎缓解了XRISM数据与当前数值模拟之间的矛盾，表明当前观测数据并不需要一个比Kolmogorov更陡峭的湍流谱。 显示英文摘要

We investigate whether the properties of turbulent gas motions recently measured via X-ray spectroscopy in the Coma cluster of galaxies by XRISM are in tension with the "classical" fluid picture of the intracluster medium on large scales, as produced by a typical high-resolution cosmological simulation. We use a high-resolution simulation of Coma-like cluster of galaxies and show that the Kolmogorov-like turbulence measured in the simulation yields to velocity structure functions and line-width that fully compatible with those measured by the XRISM observation of Coma. These results highlight the combined biases driven by the inhomogeneity of turbulence in the intracluster medium and by the X-ray weighting in observations, and appear to release the tension between the XRISM data and current numerical simulations, showing that a turbulent spectrum much steeper than Kolmogorov is not required by current observational data.

[59] arXiv:2507.04964 (交叉列表自 astro-ph.CO) [中文pdf, pdf, html, 其他]

标题： 21厘米EoR双谱在$z=8.2$处的MWA数据 I：前景和初步上限 显示英文标题

标题： The EoR 21-cm Bispectrum at $z=8.2$ from MWA data I: Foregrounds and preliminary upper limits

Sukhdeep Singh Gill, Somnath Bharadwaj, Khandakar Md Asif Elahi, Shiv K. Sethi, Akash Kumar Patwa

评论： 20页，7图，3表。欢迎提出意见

主题： 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA)

我们尝试使用Murchison Widefield Array (MWA) $154.2~\mathrm{MHz}$ 数据来测量 $z = 8.2$ 宇宙再电离时期 (EoR) 21-cm 三阶谱 (BS)。 我们发现 $B(k_{1\perp}, k_{2\perp}, k_{3\perp}, k_{1\parallel}, k_{2\parallel})$ 三维圆柱形 BS 展现出一个前景楔形，类似于 $P(k_{1\perp},k_{1\parallel})$ 的 21-cm 圆柱形功率谱。 然而，BS 前景楔形，其依赖于 $(k_{1\perp},k_{1\parallel})$, $(k_{2\perp},k_{2\parallel})$ 和 $(k_{3\perp},k_{3\parallel})$ 三角形的三条边，更为复杂。 考虑到各种前景规避情景，我们确定所有三条边都位于前景楔形之外的区域作为 21-cm BS 的 EoR 窗口。 然而，EoR 窗口受到数据中缺失频率通道周期性模式引起的周期性尖峰模式的污染。 我们对所有可能大小和形状的三角形评估了分箱的3D球面BS，并给出了$\Delta^3$的平均立方体亮度温度涨落结果。 我们获得的EoR 21-cm信号的最佳$2\sigma$上限为$\Delta^3_{\rm UL} = (1.81\times 10^3)^3~\mathrm{mK}^3$在$k_1 = 0.008~\mathrm{Mpc}^{-1}$和$\Delta^3_{\rm UL} = (2.04\times 10^3)^3~\mathrm{mK}^3$在$k_1 = 0.012~\mathrm{Mpc}^{-1}$，分别对应等边三角形和挤压三角形。 这些结果由前景主导，并且比预测的EoR 21-cm信号$(\sim 10^3 ~\mathrm{mK}^3)$大多个数量级。 显示英文摘要

We attempt to measure the $z = 8.2$ Epoch of Reionization (EoR) 21-cm bispectrum (BS) using Murchison Widefield Array (MWA) $154.2~\mathrm{MHz}$ data. We find that $B(k_{1\perp}, k_{2\perp}, k_{3\perp}, k_{1\parallel}, k_{2\parallel})$ the 3D cylindrical BS exhibits a foreground wedge, similar to $P(k_{1\perp},k_{1\parallel})$ the 21-cm cylindrical power spectrum. However, the BS foreground wedge, which depends on $(k_{1\perp},k_{1\parallel})$, $(k_{2\perp},k_{2\parallel})$ and $(k_{3\perp},k_{3\parallel})$ the three sides of a triangle, is more complicated. Considering various foreground avoidance scenarios, we identify the region where all three sides are outside the foreground wedge as the EoR window for the 21-cm BS. However, the EoR window is contaminated by a periodic pattern of spikes that arises from the periodic pattern of missing frequency channels in the data. We evaluate the binned 3D spherical BS for triangles of all possible sizes and shapes, and present results for $\Delta^3$ the mean cube brightness temperature fluctuations. The best $2\sigma$ upper limits we obtain for the EoR 21-cm signal are $\Delta^3_{\rm UL} = (1.81\times 10^3)^3~\mathrm{mK}^3$ at $k_1 = 0.008~\mathrm{Mpc}^{-1}$ and $\Delta^3_{\rm UL} = (2.04\times 10^3)^3~\mathrm{mK}^3$ at $k_1 = 0.012~\mathrm{Mpc}^{-1}$ for equilateral and squeezed triangles, respectively. These are foreground-dominated, and are many orders of magnitude larger than the predicted EoR 21-cm signal $(\sim 10^3 ~\mathrm{mK}^3)$.

[60] arXiv:2507.05051 (交叉列表自 astro-ph.EP) [中文pdf, pdf, html, 其他]

标题： 一颗在近日点附近的NH$_2$丰富的星际彗星 2I/Borisov 的画像 显示英文标题

标题： A portrait throughout perihelion of the NH$_2$-rich interstellar comet 2I/Borisov

Sophie E. Deam, Michele T. Bannister, Cyrielle Opitom, Matthew M. Knight, Ryan Ridden-Harper, Darryl Z. Seligman, Alan Fitzsimmons, Aurélie Guilbert-Lepoutre, Emmanuel Jehin, Laurent Jorda, Michael Marsset, Youssef Moulane, Philippe Rousselot, Pierre Vernazza, Bin Yang

评论： 提交至PSJ，欢迎提出意见

主题： 地球与行星天体物理学 (astro-ph.EP) ; 星系的天体物理学 (astro-ph.GA)

星际彗星2I/Borisov是第一个在其整个近日点通过过程中能够进行成分表征的星际物体。 我们报告了使用ESO VLT的积分场光谱仪MUSE进行的全面光学观测活动的所有16个时相，时间跨度为126天，从2019年11月14日到2020年3月19日。 2I/Borisov的空间尘埃发射主要平滑，没有季节性影响。 一个类似喷流的特征一直可见。 其彗发的气体生成形态也是平滑的，对于C$_2$，NH$_2$和CN来说，围绕光中心对称。 这些物质的生成率在近日点前后逐渐下降，直到2I在2020年3月初爆发和分裂事件。 C$_2$，NH$_2$和 CN的生成率都增加了，其中NH$_2$增加最为显著；尘埃发射也略微变红。 与太阳系中迄今测量的彗星相比，2I/Borisov是一个碳贫乏、相对NH$_2$含量丰富的彗星。 显示英文摘要

The interstellar comet 2I/Borisov is the first interstellar object where compositional characterisation was possible throughout its entire perihelion passage. We report all 16 epochs of a comprehensive optical observation campaign with ESO VLT's integral field spectrograph MUSE, spanning 126 days from 2019 November 14 to 2020 March 19. The spatial dust emission of 2I/Borisov was predominantly smooth, with no seasonal effect. A jet-like feature was consistently visible. The gas production morphology of its coma was also smooth and similar for C$_2$, NH$_2$, and CN: symmetric around the photocentre. The production rates of these species gently declined into and beyond perihelion, until 2I's outburst and splitting event in early 2020 March. C$_2$, NH$_2$, and CN production rates all increased, with NH$_2$ being the most significant; the dust emission also slightly reddened. 2I/Borisov is a carbon-depleted, relatively NH$_2$-rich comet when compared to those comets yet measured in the Solar System.

[61] arXiv:2507.05085 (交叉列表自 astro-ph.HE) [中文pdf, pdf, html, 其他]

标题： 蒙特卡罗辐射流体动力学模拟线驱动的盘风：放松等温近似 显示英文标题

标题： Monte-Carlo radiation hydrodynamic simulations of line-driven disc winds: relaxing the isothermal approximation

Amin Mosallanezhad, Christian Knigge, Nicolas Scepi, James H. Matthews, Knox S. Long, Stuart A. Sim, Austen Wallis

评论： 13页，6图，已接受发表于MNRAS

主题： 高能天体物理现象 (astro-ph.HE) ; 星系的天体物理学 (astro-ph.GA)

盘风在所有尺度的吸积天体物理系统中起着关键作用。 在吸积白矮星（AWDs）和活动星系核（AGN）中，光谱线上的辐射压是一种有前景的风驱机制。 然而，线驱机制的效率对流的电离状态非常敏感，使得构建这些风的可靠物理图景变得困难。 最近，我们首次提出了包含详细多维电离计算的吸积白矮星辐射流体动力学（RHD）模拟，通过完全频率依赖的辐射转移，使用Sirocco代码与PLUTO耦合。 这些模拟产生的线驱动风比之前使用更近似处理电离和辐射转移的研究结果要弱得多（对于我们采用的参数，Mdot_wind / Mdot_acc < 1e-5），而之前的研究结果为Mdot_wind / Mdot_acc ~ 1e-4。 我们工作的剩余限制之一是假设流出是等温的。 在这里，我们通过采用理想气体状态方程并显式求解流的多维温度结构来放松这一假设。 在AWD设置中，考虑风的热状态不会改变从等温近似得出的整体结论。 我们的新模拟确认了线驱效率问题：预测的流出物过于电离，这意味着它们既不能创造最佳驱动条件，也不能再现观测到的紫外线风特征。 可能的解决方案包括亚网格尺度的风团块化、比预期更软的光谱能量分布或额外的驱动机制。 随着现在将物理过程纳入我们的模拟中，我们已具备充分的能力进一步探索AGN中的线驱动盘风。 显示英文摘要

Disc winds play a crucial role in many accreting astrophysical systems across all scales. In accreting white dwarfs (AWDs) and active galactic nuclei (AGN), radiation pressure on spectral lines is a promising wind-driving mechanism. However, the efficiency of line driving is extremely sensitive to the ionization state of the flow, making it difficult to construct a reliable physical picture of these winds. Recently, we presented the first radiation-hydrodynamic (RHD) simulations for AWDs that incorporated detailed, multi-dimensional ionization calculations via fully frequency-dependent radiative transfer, using the Sirocco code coupled to PLUTO. These simulations produced much weaker line-driven winds (Mdot_wind / Mdot_acc < 1e-5 for our adopted parameters) than earlier studies using more approximate treatments of ionization and radiative transfer (which yielded Mdot_wind / Mdot_acc ~ 1e-4). One remaining limitation of our work was the assumption of an isothermal outflow. Here, we relax this by adopting an ideal gas equation of state and explicitly solving for the multi-dimensional temperature structure of the flow. In the AWD setting, accounting for the thermal state of the wind does not change the overall conclusions drawn from the isothermal approximation. Our new simulations confirm the line-driving efficiency problem: the predicted outflows are too highly ionized, meaning they neither create optimal driving conditions nor reproduce the observed ultraviolet wind signatures. Possible solutions include wind clumping on sub-grid scales, a softer-than-expected spectral energy distribution, or additional driving mechanisms. With the physics now built into our simulations, we are well-equipped to also explore line-driven disc winds in AGN.

[62] arXiv:2507.05155 (交叉列表自 astro-ph.EP) [中文pdf, pdf, html, 其他]

标题： 詹姆斯·韦布空间望远镜对自由漂浮的行星质量天体及其盘的光谱学研究 显示英文标题

标题： Spectroscopy of Free-Floating Planetary-Mass Objects and their disks with JWST

Belinda Damian, Aleks Scholz, Ray Jayawardhana, V. Almendros-Abad, Laura Flagg, Koraljka Mužić, Antonella Natta, Paola Pinilla, Leonardo Testi

评论： 已被《天文学杂志》接受发表。15页，11幅图，1张表

主题： 地球与行星天体物理学 (astro-ph.EP) ; 星系的天体物理学 (astro-ph.GA)

已知自由漂浮的行星质量天体（FFPMOs）在年轻年龄时拥有盘。在此，我们展示了八个年轻FFPMOs的1-13$\mu m$光谱，这些天体的质量为5-10 M$_\mathrm{Jup}$ （年龄为1-5 Myr），使用詹姆斯·韦布空间望远镜上的NIRSpec和MIRI仪器。我们推导了这些目标的基本特性，并发现光谱类型为M9.5到L4，有效温度为1600-1900 K。我们目标的光球光谱在相似温度下显示出明显的多样性，特别是在3-5$\mu m$范围内，这无法用现有的大气模型解释。我们在其中一个目标的光球中发现了硅酸盐吸收特征，这是非常年轻的FFPMOs中的首次检测，表明它们的冷大气中有硅酸盐云。我们的六个物体在光球之上显示出中红外过量辐射，以及硅酸盐发射特征，证明了盘的存在。后者的特征形状和强度构成了颗粒增长和结晶的有力证据，类似于在更高质量的棕矮星和恒星中所见的情况。我们还在几个目标的盘中检测到了碳氢化合物分子的发射线。这些是迄今为止发现的质量最低的孤立天体，其盘中出现了硅酸盐和碳氢化合物的发射特征。盘的存在及其特征表明，在自由漂浮的行星质量天体周围有可能形成岩石伴星。 显示英文摘要

Free-floating planetary-mass objects (FFPMOs) are known to harbor disks at young ages. Here, we present 1-13 $\mu m$ spectra for eight young FFPMOs with masses of 5-10 M$_\mathrm{Jup}$ (at ages of 1-5 Myr), using the NIRSpec and MIRI instruments on the James Webb Space Telescope. We derive fundamental properties of these targets, and find spectral types of M9.5 to L4, with effective temperatures of 1600-1900 K. The photospheric spectra of our targets show a clear diversity at similar temperatures, especially in the 3-5 $\mu m$ range, unaccounted for by existing atmospheric models. We find a silicate absorption feature in the photosphere of one of our targets, the first such detection in very young FFPMOs, indicating silicate clouds in their cool atmospheres. Six of our objects show mid-infrared excess emission above the photosphere, as well as silicate emission features, demonstrating the presence of disks. The shape and strength of the latter features constitute strong evidence of grain growth and crystallization, similar to what is seen in more massive brown dwarfs and stars. We also detect emission lines from hydrocarbon molecules in the disks of several targets. These are the lowest mass isolated objects found so far with silicate and hydrocarbon emission features arising in their disks. The presence of disks and their characteristics point to the potential for the formation of rocky companions around free-floating planetary-mass objects.

[63] arXiv:2507.05199 (交叉列表自 gr-qc) [中文pdf, pdf, html, 其他]

标题： 均匀磁场中的克尔黑洞：一个精确解 显示英文标题

标题： Kerr black hole in a uniform magnetic field: An exact solution

Jiri Podolsky, Hryhorii Ovcharenko

评论： 7页，1图

主题： 广义相对论与量子宇宙学 (gr-qc) ; 星系的天体物理学 (astro-ph.GA) ; 高能物理 - 理论 (hep-th)

一个在爱因斯坦引力中的新精确时空类被提出，这些时空是处于外部磁场（或电场）中的Kerr黑洞，该磁场在远处是均匀的，并沿着旋转轴方向。 这些是轴对称稳态的爱因斯坦-麦克斯韦方程解，其中法拉第张量的零方向既不与代数类型D的威耳逊张量的两个主零方向对齐（不同于Kerr-Melvin时空）。 三个物理参数分别是黑洞质量$m$、其旋转$a$和外部场值$B$。 当$B$为零时，度规直接简化为标准的Boyer-Lindquist形式的Kerr黑洞，而当$m$为零时，我们得到具有均匀麦克斯韦场的共形平坦的Bertotti-Robinson宇宙。 当$a$为零时，时空包含在Van den Bergh-Carminati解中，该解可以理解为处于磁场中的施瓦茨希尔德黑洞。 我们的非对齐麦克斯韦毛发的黑洞族——可以称为Kerr-Bertotti-Robinson（Kerr-BR）黑洞——可能在从数学相对论到相对论天体物理的各种研究中找到应用。 显示英文摘要

A new class of exact spacetimes in Einstein's gravity, which are Kerr black holes immersed in an external magnetic (or electric) field that is asymptotically uniform and oriented along the rotational axis, is presented. These are axisymmetric stationary solutions to the Einstein-Maxwell equations such that the null directions of the Faraday tensor are not aligned with neither of the two principal null directions of the Weyl tensor of algebraic type D (unlike the Kerr-Melvin spacetime). Three physical parameters are the black hole mass $m$, its rotation $a$, and the external field value $B$. For vanishing $B$ the metric directly reduces to standard Boyer-Lindquist form of the Kerr black hole, while for zero $m$ we recover conformally flat Bertotti-Robinson universe with a uniform Maxwell field. For zero $a$ the spacetime is contained in the Van den Bergh-Carminati solution which can be understood as the Schwarzschild black hole in a magnetic field. Our family of black holes with non-aligned Maxwell hair - that can be called the Kerr-Bertotti-Robinson (Kerr-BR) black holes - may find application in various studies ranging from mathematical relativity to relativistic astrophysics.

[64] arXiv:2507.05226 (交叉列表自 astro-ph.EP) [中文pdf, pdf, html, 其他]

标题： 3I/ATLAS星际物体的初始VLT/MUSE光谱观测 显示英文标题

标题： Initial VLT/MUSE spectroscopy of the interstellar object 3I/ATLAS

Cyrielle Opitom, Colin Snodgrass, Emmanuel Jehin, Michele T. Bannister, Erica Bufanda, Sophie E. Deam, Rosemary Dorsey, Marin Ferrais, Said Hmiddouch, Matthew M. Knight, Rosita Kokotanekova, Brayden Leicester, Michaël Marsset, Brian Murphy, Vincent Okoth, Ryan Ridden-Harper, Mathieu Vander Donckt, Léa Ferellec, Damien Hutsemekers, Manuela Lippi, Jean Manfroid, Zouhair Benkhaldoun

评论： 提交至MNRAS

主题： 地球与行星天体物理学 (astro-ph.EP) ; 星系的天体物理学 (astro-ph.GA)

星际彗星3I/ATLAS是第三个被发现的星际物体。 近日点前的测量提供了一个独特的机会来研究它的活动和成分，这些可能在接下来的几个月中因受热而发生变化。 我们提供了光学光谱观测的初步基准，这些观测是在发现后仅两天使用VLT上的MUSE仪器于2025年7月3日进行的，当时3I距离太阳4.47天文单位，距离地球3.46天文单位。 这些观测证实了3I的彗星性质，并揭示了一个红色的彗发，其光谱斜率为$(18\pm4)\%/1000$~\AA ，比大多数太阳系彗星更红，但与一些太阳系海王星外天体或半人马小行星的表面颜色相似。 我们搜索了C$_2$、NH$_2$、CN和[OI]的气体发射，但未检测到，这与在这一日心距离下太阳系彗星的挥发性物质未检测到一致。 目前，彗发似乎完全是尘埃组成的。 随着3I逐渐接近太阳，未来的观测将提供一个无价的机会来观察其活动性的演变，研究其成分，测试星际物体种群模型的预测，并将3I与太阳系彗星进行比较。 显示英文摘要

The interstellar comet 3I/ATLAS is only the third interstellar object to be discovered. Pre-perihelion measurements provide a unique opportunity to study its activity and composition, which may alter as it is heated in the coming months. We provide an initial baseline from optical spectroscopic observations obtained only two days after discovery, using the MUSE instrument on the VLT on 2025 July 3, while 3I was at 4.47 au from the Sun and 3.46 au from the Earth. These observations confirm the cometary nature of 3I, and reveal a red coma with a spectral slope of $(18\pm4)\%/1000$~\AA, redder than most Solar System comets but similar to the surface colour of some Solar System Trans-Neptunian Objects or Centaurs. We searched for but did not detect gas emission from C$_2$, NH$_2$, CN, and [OI], which is consistent with volatile non-detections for Solar System comets at this heliocentric distance. At present, the coma appears entirely dusty. Future observations of 3I as it comes closer to the Sun will provide an invaluable opportunity to witness the evolution of its activity, study its composition, test predictions of interstellar object population models, and compare 3I to Solar System comets.

[65] arXiv:2507.05252 (交叉列表自 astro-ph.EP) [中文pdf, pdf, html, 其他]

标题： 星际彗星3I/ATLAS：发现和物理描述 显示英文标题

标题： Interstellar comet 3I/ATLAS: discovery and physical description

Bryce T. Bolin, Matthew Belyakov, Christoffer Fremling, Matthew J. Graham, Candace L. Gray, Carl Ingebretsen, Gracyn Jewett, Mukremin Kilic, Carey M. Lisse, Diana Roderick, Ahmed. M. Abdelaziz, Laura-May Abron, Michael W. Coughlin, Eslam Elhosseiny, Cheng-Han Hsieh, Martin Mašek, Mona Molham, Ali Takey, Keith S. Noll, Ian Wong

评论： 8页，4图，2表，提交至MNRAS:L

主题： 地球与行星天体物理学 (astro-ph.EP) ; 星系的天体物理学 (astro-ph.GA) ; 天体物理学的仪器与方法 (astro-ph.IM)

我们描述了星际彗星3I\ATLAS 的物理特性，该彗星于2025年7月1日由小行星地球撞击最后预警系统发现。 彗星的偏心率，$e$ $\simeq$ 6.08 和无限远处的速度，v$_{\infty}$ $\simeq$ 57 km/s，表明其具有星际起源。 我们在2025年7月3日使用帕洛马200英寸下一代帕洛马光谱仪获得了g、r、i测光数据。 我们测量了颜色指数 g-r = 0.43$\pm$0.02 mag，r-i = 0.16$\pm$0.02 mag，以及 g-i = 0.59$\pm$0.03 mag 和光谱斜率为 1.3$\pm$0.9$\%$/100 nm。 我们计算了彗星 10,000 km 范围内的尘埃截面为 230.0$\pm$5.2 km$^2$，假设反照率为 0.10。 3I\ATLAS 的检测 FWHM 为$\sim$2.2 角秒，在我们的 r 波段图像中测量得到，其 A(0$^\circ$)f$\rho$为 287.2$\pm$2.8 平方厘米。 最后，我们利用彗发的朝向太阳的范围来限制尘埃喷射速度，发现\textmu 量级的颗粒具有$\sim$0.01-1 m/s，这意味着彗星的尘埃质量损失率是$\sim$0.1 - 1.0 kg/s. 显示英文摘要

We describe the physical characteristics of interstellar comet 3I\ATLAS, discovered on 2025 July 1 by the Asteroid Terrestrial-impact Last Alert System. The comet has eccentricity, $e$ $\simeq$ 6.08 and velocity at infinity, v$_{\infty}$ $\simeq$ 57 km/s, indicating an interstellar origin. We obtained g, r, i photometry with the Palomar 200-inch Next Generation Palomar Spectrograph on 2025 July 3. We measured colour indices g-r = 0.43$\pm$0.02 mag, r-i = 0.16$\pm$0.02 mag, and g-i = 0.59$\pm$0.03 mag and a spectral slope of 1.3$\pm$0.9 $\%$/100 nm. We calculate the dust cross-section within 10,000 km of the comet to be 230.0$\pm$5.2 km$^2$, assuming an albedo of 0.10. The FWHM of 3I\ATLAS's detection is $\sim$2.2 arcsec as measured in our r-band images and has A(0$^\circ$)f$\rho$ of 287.2$\pm$2.8 cm. Finally, we use the sunward extent of the coma to constrain the dust ejection speed, finding that \textmu m-scale to mm-scale particles have $\sim$0.01-1 m/s, implying the comet's dust mass-loss rate is $\sim$0.1 - 1.0 kg/s.

替换提交 (展示 25 之 25 条目 )

[66] arXiv:2402.05996 (替换) [中文pdf, pdf, html, 其他]

标题： 尘埃吸收在$z \sim 2$-$12$JWST星系中的演化 显示英文标题

标题： Dust attenuation evolution in $z \sim 2$-$12$ JWST galaxies

V. Markov, S. Gallerani, A. Ferrara, A. Pallottini, E. Parlanti, F. Di Mascia, L. Sommovigo, M. Kohandel

评论： 16页，5图；

期刊参考： 自然天文学，第8卷，2024年

主题： 星系的天体物理学 (astro-ph.GA)

大量由星系中的恒星合成的重元素凝结成亚微米大小的固态颗粒，称为尘埃颗粒。 尘埃对星系辐射产生波长依赖性的衰减，$A_\lambda$，从而显著改变其观测特性。 在本地， $A_\lambda$通常是由幂律和由小的碳基颗粒产生的紫外特征（“峰”）组成。 然而，关于其随宇宙时间演化的信息很少。 在这里，利用詹姆斯·韦布空间望远镜在红移范围 z = 2 - 12 观测到的 173 个星系的数据，我们报告了在 z ~ 7.55 星系中紫外峰的最远检测（当时宇宙仅约 700 Myr 老），并首次展示了幂律斜率和峰强度随着高红移而降低。 我们提出，早期时期平坦的$A_\lambda$形状是由超新星抛射物中新形成的较大颗粒产生的，这些颗粒在如此早期时期作为主要的尘埃工厂。 重要的是，由于可用宇宙时间有限，这些颗粒在星际介质中经历了最小的再处理。 这一发现为宇宙尘埃起源和演化的研究开辟了新的视角。 显示英文摘要

A sizable fraction of the heavy elements synthesized by stars in galaxies condenses into sub-micron-sized solid-state particles, known as dust grains. Dust produces a wavelength-dependent attenuation, $A_\lambda$, of the galaxy emission, thereby significantly altering its observed properties. Locally, $A_\lambda$ is in general the sum of a power-law and a UV feature ('bump') produced by small, carbon-based grains. However, scant information exists regarding its evolution across cosmic time. Here, leveraging data from 173 galaxies observed by the James Webb Space Telescope in the redshift range z = 2 - 12, we report the most distant detection of the UV bump in a z ~ 7.55 galaxy (when the Universe was only ~ 700 Myr old), and show for the first time that the power-law slope and the bump strength decrease towards high redshifts. We propose that the flat $A_\lambda$ shape at early epochs is produced by large grains newly formed in supernova ejecta, which act as the main dust factories at such early epochs. Importantly, these grains have undergone minimal reprocessing in the interstellar medium due to the limited available cosmic time. This discovery opens new perspectives in the study of cosmic dust origin and evolution.

[67] arXiv:2410.20530 (替换) [中文pdf, pdf, html, 其他]

标题： 在宇宙黎明时期大质量星系高恒星形成效率的起源 显示英文标题

标题： On the Origin of the High Star-Formation Efficiency in Massive Galaxies at Cosmic Dawn

Zachary Lee Andalman, Romain Teyssier, Avishai Dekel

评论： 26页正文，33页总计，21幅图表。于2025年6月4日被MNRAS接收。于2025年5月3日重新提交进行第二次评审。于2024年10月27日首次提交评审。欢迎提出意见。相关视频请见https://www.youtube.com/playlist?list=PL7YbfRC6zxzAYgFEr5oefYb5dcv0dl7Ba。相关数据请见https://doi.org/10.34770/v56h-ps15。

期刊参考： MNRAS，540，3350-3383（2025）

主题： 星系的天体物理学 (astro-ph.GA)

受JWST早期观测到的明亮星系过多的启发，我们在宇宙黎明时期对一个大质量星系进行聚焦宇宙学模拟，在 $10^{11} M_\odot$ 的晕中 $z = 9$，使用流体引力代码RAMSES，在有效分辨率 $\sim 10~{\rm pc}$ 下进行。我们研究了增强该星系恒星形成区域高气体密度下的恒星形成效率（SFEs）的物理机制（ $\sim 3\times 10^3~{\rm cm^{-3}}$， $\sim 10^4~M_\odot/{\rm pc^2}$）。我们的标准恒星形成方案使用了一个基于湍流的、多自由落体的物理动机模型，避免从较低红移进行人为外推。 根据$z = 9$，我们的模拟星系是一个具有高恒星质量$\sim 3\times 10^9~M_\odot$和高恒星形成率$\sim 50~M_\odot/{\rm yr}$的不均匀、厚实、旋转的盘状结构。 高气体密度使得超新星（SN）反馈效率较低，从而产生较高的局部 SFE$\gtrsim 10\%$。 全局 SFE 由反馈驱动的外流决定，并且与局部 SFE 的相关性较弱。 光致电离加热使 SN 反馈更有效，但综合 SFE 始终保持较高。 宇宙黎明时期的强烈吸积引发湍流，从而降低局部 SFE，但这仅对全局 SFE 产生微弱影响。 尽管分辨率有限，我们模拟星系的恒星形成历史与宇宙黎明时期观测到的巨星级星系相似。 我们为未来的模拟奠定了基础，这些模拟将自洽地处理辐射并使用更高的有效分辨率$\sim 1~{\rm pc}$，以捕捉恒星形成云的物理过程。 显示英文摘要

Motivated by the early excess of bright galaxies seen by JWST, we run zoom-in cosmological simulations of a massive galaxy at Cosmic Dawn, in a halo of $10^{11} M_\odot$ at $z = 9$, using the hydro-gravitational code RAMSES at an effective resolution $\sim 10~{\rm pc}$. We investigate physical mechanisms that enhance the star-formation efficiencies (SFEs) at the high gas densities of the star-forming regions in this galaxy ($\sim 3\times 10^3~{\rm cm^{-3}}$, $\sim 10^4~M_\odot/{\rm pc^2}$). Our fiducial star formation recipe uses a physically-motivated, turbulence-based, multi-freefall model, avoiding ad hoc extrapolation from lower redshifts. By $z = 9$, our simulated galaxy is a clumpy, thick, rotating disc with a high stellar mass $\sim 3\times 10^9~M_\odot$ and high star formation rate $\sim 50~M_\odot/{\rm yr}$. The high gas density makes supernova (SN) feedback less efficient, producing a high local SFE $\gtrsim 10\%$. The global SFE is set by feedback-driven outflows and only weakly correlated with the local SFE. Photoionization heating makes SN feedback more efficient, but the integrated SFE always remains high. Intense accretion at Cosmic Dawn seeds turbulence which reduces local SFE, but this only weakly affects the global SFE. The star formation histories of our simulated galaxies are similar to observed massive galaxies at Cosmic Dawn, despite our limited resolution. We set the stage for future simulations which treat radiation self-consistently and use a higher effective resolution $\sim 1~{\rm pc}$ that captures the physics of star-forming clouds.

[68] arXiv:2411.12741 (替换) [中文pdf, pdf, html, 其他]

标题： RR L型造父变星在中等年龄麦哲伦星团中的成员概率和延迟时间分布 显示英文标题

标题： RR Lyrae Stars in Intermediate-age Magellanic Clusters: Membership Probabilities and Delay Time Distribution

Bolivia Cuevas-Otahola, Cecilia Mateu, Ivan Cabrera-Ziri, Gustavo Bruzual, Fabiola Hernández-Pérez, Gladis Magris, Holger Baumgardt

评论： 15页，8图，已被接受发表于MNRAS

主题： 星系的天体物理学 (astro-ph.GA)

最近的研究通过提出这些恒星中有一部分属于中等年龄（$\sim$2-5~Gyr）挑战了我们对RR Lyrae（RRL）恒星作为仅属于古老种群（$\gtrsim10$~Gyr）示踪者的规范观点。 由于目前尚无法直接推断个别RRL恒星的年龄，因此本研究的目标是寻找与中等年龄星团相关联的RRL恒星，这些星团的可靠年龄可以安全地归因于RRL恒星。 我们使用了Gaia DR3特定对象研究和OGLE IV公开目录，在大麦哲伦星云和小麦哲伦星云中搜索年龄超过1~Gyr的恒星星团周围的RRL恒星。 基于自行和光度距离建模成员概率，我们获得了一份与麦哲伦星团相关的259个RRL恒星列表。 其中，23个RRL恒星可能属于10个中等年龄的星团：分别在小麦哲伦星云和大麦哲伦星云中有3个和7个。 通过建模每个星团中RRL恒星数量的推断期望值，我们推断了三个年龄范围内的RRL恒星的延迟时间分布。 对于古老种群（$>8$~Gyr），我们发现$2.5^{+0.4}_{-0.3}$RRL$/10^5 M_\odot$。 对于年轻（1-2 Gyr）和中等年龄（2-8 Gyr）的星群，我们发现经过进一步从控制场测试中去污染后的$0.34^{+0.17}_{-0.12}$和$0.071^{+0.073}_{-0.041}$RRL$/10^5 M_\odot$的比率分别为，。虽然径向速度对于明确确认星团成员身份是必要的，但这里提供的中等年龄 RRL 星星的高概率列表为首次直接确认这些神秘恒星提供了有希望的机会。 显示英文摘要

Recent works have challenged our canonical view of RR Lyrae (RRL) stars as tracers of exclusively old populations ($\gtrsim10$~Gyr) by proposing a fraction of these stars to be of intermediate ages ($\sim$2-5~Gyr). Since it is currently not possible to infer stellar ages directly for individual RRL stars, our goal in this work is to search for these in association to intermediate-age clusters whose reliable ages can then be safely be attributed to the RRL. We used the Gaia DR3 Specific Object Study and OGLE IV public catalogues to search for RRL stars around stellar clusters older than 1~Gyr in the Large and Small Magellanic Clouds. Modelling membership probabilities based on proper motion and photometric distance we obtained a list of 259 RRL stars associated with Magellanic clusters. Of these, 23 RRL are likely members of 10 intermediate-age clusters: 3 and 7 in the Small and Large Magellanic Clouds, respectively. By modelling the inferred expectation values of the number of RRL stars per cluster, we inferred the delay time distribution of the RRL in three age ranges. For the old population ($>8$~Gyr) we find $2.5^{+0.4}_{-0.3}$ RRL$/10^5 M_\odot$. For the young (1-2 Gyr) and intermediate age (2-8 Gyr) populations we find rates of $0.34^{+0.17}_{-0.12}$ and $0.071^{+0.073}_{-0.041}$ RRL$/10^5 M_\odot$, respectively, after further decontamination from control field tests. While radial velocities are necessary for definitively confirming cluster memberships, the high-probability list of intermediate-age RRL stars presented here offers a promising opportunity for the first direct confirmation of these enigmatic stars.

[69] arXiv:2501.12138 (替换) [中文pdf, pdf, html, 其他]

标题： 从惯性流入形成球状星团：吸积极大质量恒星是丰度异常的起源 显示英文标题

标题： Globular cluster formation from inertial inflows: accreting extremely massive stars as the origin of abundance anomalies

Mark Gieles (ICREA, Barcelona), Paolo Padoan (Barcelona, Dartmouth), Corinne Charbonnel (Geneva), Jorick S. Vink (Armagh), Laura Ramírez-Galeano (Geneva)

评论： 30页，20张图，根据有利的审稿人报告重新提交至MNRAS。针对“球状星团多重种群问题”的新思路

主题： 星系的天体物理学 (astro-ph.GA) ; 太阳与恒星天体物理学 (astro-ph.SR)

我们使用大质量恒星形成中的惯性-流入模型来描述球状星团（GCs）在湍动分子云中的形成。该模型的一个关键方面是最大恒星质量与云质量成线性比例，因此在大质量GCs（$\gtrsim10^5\,\msun$）中会形成极端大质量恒星（EMSs，$10^{3-4}\,\msun$）。总风质量损失主要由吸积的极端大质量恒星（aEMSs）主导，其风质量损失率已变得与其吸积率相当（$\gtrsim10^{-2}\,\msun\,\yr^{-1}$）。这些风在GC形成期间用高温氢燃烧产物污染星团内介质。我们提出了一种参数化模型，用于描述GC形成过程中恒星质量函数的演化（$\sim 1-2\,\myr$），考虑了气体流入、风质量损失以及aEMS产物与具有初始原GC丰度的原始气体的混合。低质量恒星（$\lesssim1\,\msun$）由此混合气体连续形成，它们的丰度与GC质量及金属量的观测丰度趋势相似，具体为：(i) 典型GC中的氦散布较小（$\Delta Y \simeq 0.01$），并随GC质量增加；(ii) 污染恒星的比例随GC质量及金属量增加；(iii) 镁-铝反相关性的范围在贫金属和大质量GC中更为明显。 我们得出结论，GCs 是由来自表面密度为$\gtrsim10^3\,\msun\,\pc^{-2}$的气体的 EMSs 形成的，而詹姆斯·韦伯空间望远镜（{\it JWST}）发现的富氮星系主要由在星系形成最早阶段形成的 EMS 丰富的 GCs 组成。这些 EMS 可能在其后留下了质量超过对不稳定性间隙（$\gtrsim120\,\msun$）的中等质量黑洞，这些黑洞可能通过正在进行的引力波实验被发现。 显示英文摘要

We use the inertial-inflow model of massive star formation to describe the formation of globular clusters (GCs) in turbulent molecular clouds. A key aspect of this model is that the maximum stellar mass scales linearly with cloud mass, such that extremely massive stars (EMSs, $10^{3-4}\,\msun$) form in massive GCs ($\gtrsim10^5\,\msun$). The total wind mass loss is dominated by accreting EMSs (aEMSs), whose wind mass-loss rates have become comparable to their accretion rates ($\gtrsim10^{-2}\,\msun\,\yr^{-1}$). These winds pollute the intra-cluster medium with hot-hydrogen burning yields during GC formation. We propose a parameterised model for the evolution of the stellar mass function during GC formation ($\sim 1-2\,\myr$), accounting for gas inflow, wind mass loss and mixing of aEMS yields with pristine gas that has initial proto-GC abundances. Low-mass stars ($\lesssim1\,\msun$) form continuously from this mixed gas and their abundances resemble observed abundance trends with GC mass and metallicity, specifically: (i) the helium spread in a typical GC is small ($\Delta Y \simeq 0.01$) and increases with GC mass; (ii) the fraction of polluted stars increases with GC mass and metallicity; (iii) the extent of the Mg-Al anticorrelations is more pronounced in metal-poor and massive GCs. We conclude that GCs formed with a population of EMSs from gas with surface densities $\gtrsim10^3\,\msun\,\pc^{-2}$ and that nitrogen-rich galaxies discovered by the James Webb Space Telescope ({\it JWST}) are dominated by EMS-rich GCs that formed in the earliest phases of galaxy formation. These EMSs may have left behind intermediate-mass black holes with masses above the pair-instability gap ($\gtrsim120\,\msun$) that could be found with ongoing gravitational wave experiments.

[70] arXiv:2502.14961 (替换) [中文pdf, pdf, html, 其他]

标题： SOFIA/HAWC+ 远红外偏振大区域CMZ探索调查。 V. 人马座C复合体中的磁场强度和形态 显示英文标题

标题： SOFIA/HAWC+ Far-Infrared Polarimetric Large Area CMZ Exploration Survey. V. The Magnetic Field Strength and Morphology in the Sagittarius C Complex

Roy J. Zhao, Mark R. Morris, David T. Chuss, Dylan M. Paré, Jordan A. Guerra, Natalie O. Butterfield, Edward J. Wollack, Kaitlyn Karpovich

评论： 已接受发表于《天体物理学杂志》。30页，18幅图

主题： 星系的天体物理学 (astro-ph.GA)

我们使用安装在平流层红外天文台（SOFIA）上的高分辨率机载宽波段摄像机（HAWC+）仪器获取的214$\mu$m极化数据，对银河系中心分子区（CMZ）中的人马座C复合体（Sgr C；G359.43-0.09）的磁场强度和形态进行了分析。我们对单个云进行了修改后的Davis-Chandrasekhar-Fermi（DCF）分析，发现天平面磁场强度从推断强度为$\sim30~\mu{\rm G}$的高度湍流区域到相对均匀场方向的区域，强度为$\sim 300~\mu{\rm G}$。在Sgr C区域内测量了数百个磁场伪矢量，以追踪冷分子云内的投影磁场方向，正如整个CMZ的趋势一样，它们在云的边缘表现出更高的偏振分数。磁场方向表明，来自活跃恒星形成区域的喷流，如G359.43-0.10扩展绿色对象（EGO）和原恒星源FIR-4（G359.43+0.02），在其附近引起高湍流。发现磁场方向与Sgr C HII区域的表面相切，该区域与HII区域中报道的两个[CII]发射空腔在空间上对应，表明HII区域与周围致密云之间的压缩前沿。Sgr C附近的其他特征，特别是众多非热射电丝状物（NTFs）以及HII区域正西南方向的弥散X射线发射源，也根据磁场测量结果进行了讨论。 显示英文摘要

We present an analysis of the magnetic field strength and morphology in the Sagittarius C complex (Sgr C; G359.43-0.09) in the Milky Way Galaxy's Central Molecular Zone (CMZ), using the 214 $\mu$m polarimetry data acquired with the High-resolution Airborne Wide-band Camera (HAWC+) instrument aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). We conduct a modified Davis-Chandrasekhar-Fermi (DCF) analysis of individual clouds and find that the sky-plane magnetic field strength varies from highly turbulent regions having inferred strengths of $\sim30~\mu{\rm G}$ to regions of relatively uniform field orientation having strengths of $\sim 300~\mu{\rm G}$. Several hundred magnetic field pseudovectors in the Sgr C region were measured to trace the projected magnetic field orientation within cold molecular clouds, and as is the trend throughout the CMZ, they show a higher polarization fraction toward the periphery of the clouds. The magnetic field orientations suggest that outflows from active star-forming regions, such as the G359.43-0.10 extended green object (EGO) and the protostellar source FIR-4 (G359.43+0.02), cause high turbulence in their vicinity. The magnetic field direction is found to be tangential to the surface of the Sgr C HII region, which displays spatial correspondence with two [CII] emission cavities reported in the HII region, signifying a compression front between the HII region and the surrounding dense clouds. Several other features in the vicinity of Sgr C, especially numerous non-thermal radio filaments (NTFs) and a diffuse source of X-ray emission to the immediate southwest of the HII region, are discussed with regard to the magnetic field measurements.

[71] arXiv:2503.03066 (替换) [中文pdf, pdf, html, 其他]

标题： 低红移后星爆星系拥有丰富的中性氢储层 显示英文标题

标题： Low redshift post-starburst galaxies host abundant HI reservoirs

Sara L. Ellison, Qifeng Huang, Dong Yang, Jing Wang, Vivienne Wild, Ben F. Rasmussen, Maria-Jesus Jimenez-Donaire, Kate Rowlands, Scott Wilkinson, Toby Brown, Ho-Hin Leung

评论： 发表于《天体物理学开放期刊》

主题： 星系的天体物理学 (astro-ph.GA)

研究后星暴（PSB）星系的气体含量可以提供关于快速熄灭过程的宝贵线索。尽管以前的研究已经研究了PSB的分子气体含量，但只有少数HI测量数据存在。在这里，我们介绍了44个PSB的新五百米口径球面射电望远镜（FAST）21厘米观测结果，导致43个检测或灵敏的上限的HI，我们将这些与25个档案测量数据结合，总共有68个PSB MHI测量数据。HI在57/68个星系中被检测到，HI质量从MHI ~10^8.5到10^10 Msun不等，气体分数（fHI = MHI/M*）从几百分比到几乎30%。因此，尽管不再形成恒星，后星暴仍然保留了大量的原子气体储层。通过与xGASS中一个恒星质量匹配的星系形成星系样本进行比较，我们发现PSB的气体分数平均低约~0.2-0.4 dex，这与它们的前身种群相比有轻微的减少是一致的。然而，PSB表现出HI特性的多样性；大约一半的HI气体质量在星系形成种群的预期波动范围内，其余的50%则多出10倍的气体贫乏。与绿色山谷中的星系相比，大约三分之二的PSB具有在预期范围内的气体分数，其余三分之一多出10倍的气体丰富。我们的结果表明，PSB中的熄灭不是原子气体储层整体去除的结果，该种群的原子气体分数涵盖了从星系形成到绿色山谷星系的范围。我们发现HI气体质量与爆发后的时间之间没有相关性；即使是在爆发后10亿年的星系，也可以保持HI正常。许多PSB中仍存在的显著气体储层为未来恒星形成的重新点燃提供了可能性。 显示英文摘要

Studying the gas content of post-starburst (PSB) galaxies can provide valuable clues regarding the process of fast quenching. Although previous works have studied the molecular gas content of PSBs, only a handful of HI measurements exist. Here, we present new Five hundred metre Aperture Spherical Telescope (FAST) 21cm observations of 44 PSBs, leading to 43 detections or sensitive upper limits of HI, which we combine with 25 archival measurements, for a total sample of 68 PSB MHI measurements. HI is detected in 57/68 galaxies, with HI masses ranging from MHI ~10^8.5 up to 10^10 Msun and gas fractions (fHI = MHI/M*) from a few percent up to almost 30 percent. Post-starbursts therefore retain ample atomic gas reservoirs, despite no longer forming stars. By comparing with a stellar mass-matched sample of star-forming galaxies in xGASS, we find that PSBs have, on average, gas fractions lower by ~0.2-0.4 dex, consistent with a mild reduction compared with their progenitor population. However, PSBs show a diversity of HI properties; about half have HI gas masses within the expected scatter of the star-forming population with the remaining 50 per cent up to a factor of 10 more gas-poor. Compared with galaxies in the green valley, about two thirds of PSBs have gas fractions within the expected range, with the remaining third up to a factor of 10 more gas-rich. Our results demonstrate that quenching in PSBs is not the result of wholesale removal of the atomic gas reservoir and that the population has atomic gas fractions that span the range from star-forming to green valley galaxies. We find no correlation between HI gas mass and time since burst; even galaxies a Gyr past their burst can remain HI-normal. The significant gas reservoirs remaining in many PSBs leaves open the possibility for future rekindling of star formation.

[72] arXiv:2503.04032 (替换) [中文pdf, pdf, html, 其他]

标题： 红移6.7处多星系合并中的扩展富气区域 显示英文标题

标题： Extended Enriched Gas in a Multi-Galaxy Merger at Redshift 6.7

Weida Hu, Casey Papovich, Lu Shen, Zixuan Peng, L. Y. Aaron Yung, Brian C. Lemaux, Justin Spilker, Justin Cole

评论： 25页，12幅图和1张表。已提交。欢迎提出意见！

主题： 星系的天体物理学 (astro-ph.GA)

最近的JWST观测揭示了具有多个恒星形成结块的高红移星系，其中许多似乎正在进行合并。 这种合并，尤其是质量相当的两个星系的合并，在推动星系演化和调节其环境的化学成分方面起着关键作用。 在此，我们报告了一个至少五个星系的重大合并，称为JWST的五重星系（JQ），位于红移6.7处，在JWST GOODS-South区域发现。 这个系统位于一个小区域内$\sim4.5''\times4.5''$ ($24.6\times24.6$ pkpc$^2$)，包含超过17个星系大小的结块，总恒星质量为$10^{10}\ M_\odot$。 JQ系统的总恒星形成速率为240 -- 270 $M_\odot$ yr$^{-1}$，使其在该时期的中位恒星形成率-质量主序线上方高出$\sim1$ dex。 JQ星系的高质量和恒星形成速率与在红移4-5处观测到的那些意想不到的高质量休眠星系的恒星形成历史一致，为这些星系的形成提供了一个合理的演化路径。 我们还检测到一个较大的 [O III]+H$\beta$发射的气体晕，环绕并连接着JQ中的四个星系，表明周围介质——其星系际介质（CGM）的内部区域存在重元素。 这为通过合并引起的潮汐剥离使星系环境金属富集提供了直接证据，时间仅在大爆炸后8亿年。 显示英文摘要

Recent JWST observations have uncovered high-redshift galaxies characterized by multiple star-forming clumps, many of which appear to be undergoing mergers. Such mergers, especially those of two galaxies with equivalent masses, play a critical role in driving galaxy evolution and regulating the chemical composition of their environments. Here, we report a major merger of at least five galaxies, dubbed JWST's Quintet (JQ), at redshift 6.7, discovered in the JWST GOODS-South field. This system resides in a small area $\sim4.5''\times4.5''$ ($24.6\times24.6$ pkpc$^2$), containing over 17 galaxy-size clumps with a total stellar mass of $10^{10}\ M_\odot$. The JQ system has a total star formation rate of 240 -- 270 $M_\odot$ yr$^{-1}$, placing it $\sim1$ dex above the median star formation rate-mass main sequence at this epoch. The high mass and star formation rate of the JQ galaxies are consistent with the star formation history of those unexpected massive quiescent galaxies observed at redshift 4-5, offering a plausible evolutionary pathway for the formation of such galaxies. We also detect a large [O III]+H$\beta$ emitting gaseous halo surrounding and connecting four galaxies in the JQ, suggesting the existence of heavy elements in the surrounding medium -- inner part of its circumgalactic medium (CGM). This provides direct evidence for the metal enrichment of galaxies' environments through merger-induced tidal stripping, just 800 Myr after the Big Bang.

[73] arXiv:2503.04887 (替换) [中文pdf, pdf, 其他]

标题： 三毫米终极莫帕拉银河系调查。 第三部分。 数据发布6，物理条件图集，全局质量转换定律以及第四象限分子星际介质的三维物理结构 显示英文标题

标题： The Three-mm Ultimate Mopra Milky Way Survey. III. Data Release 6, An Atlas of Physical Conditions, Global Mass Conversion Laws, and 3D Physical Architecture of the Molecular ISM in the Fourth Quadrant

Peter J. Barnes, Dylan G. H. Barnes, Audra K. Hernandez, Sebastian Lopez, Erik Muller

评论： 替换为《ApJS》接受的版本，经过适度修改。主论文16页，11图。附录A 15页，11图。附录B 11页，10图。附录C 45页，36图

主题： 星系的天体物理学 (astro-ph.GA)

我们介绍了ThrUMMS的数据发布6版，包括来自银河系第四象限(4Q)的分子云中完整数据立方体和各种线发射矩（$^{12}$CO,$^{13}$CO, C$^{18}$O），覆盖60$^{\circ}$$\times$ 2$^{\circ}$的范围，分辨率为72$''$在(l,b)坐标下，以及0.09 km/s$^{-1}$在V$_{LSR}$方向。 从LTE辐射传输分析的数据立方体中，我们计算了线的吸收系数、激发温度和柱密度的立方体和矩，$N_{12CO}$。 结合$I_{12CO}$和$N_{12CO}$数据，我们推导出一个全局质量转换定律$N$=$N_{0}I^{p}$，其中$N_{0}$$\approx$ 10$^{18}$mol/m$^{2}$以及$p$=2 在此分辨率下。 我们认为标准线性$N$=$XI$仅在粗略分辨率或非典型位置（如银河系中心云）下近似有效：$p$$\sim$ 1.5-1.0。 此外，$I_{12CO}$和$N_{12CO}$的速度弥散分布差异很大，前者优先追踪更稀薄的分子气体。 我们重新评估了4Q的银河系旋转参数，定义了一个新的“BGT”模型，并使用标准的动力学方法将(l,V)数据投影到(l,d)和(x,y)网格上。 为了在太阳圈内自动消除距离歧义，我们开发了一个简单的$\zeta^{+}$判别函数，并将其应用于我们的投影结果。 我们发现了分子云群体的两个之前未被识别的特征：波长为4kpc、振幅为50pc的中平面广泛波动，可能是由Sgr矮星系最近的近心点通过产生的；以及三个遥远的、大质量的分子结构，即Far Ara云，其中两个表现出异常的速度梯度，可能位于银河系的棒的远端或距离盘20-300 kpc之外的一个富含气体的矮星系$\sim$ 显示英文摘要

We present Data Release 6 of ThrUMMS, consisting of complete data cubes and various moments of line emission ($^{12}$CO, $^{13}$CO, C$^{18}$O) from molecular clouds, across 60$^{\circ}$$\times$2$^{\circ}$ of the Fourth Quadrant (4Q) of the Milky Way at a resolution of 72$''$ in (l,b) and 0.09 kms$^{-1}$ in V$_{LSR}$. From LTE radiative transfer analysis of the data cubes, we compute cubes and moments of the lines' opacity, excitation temperature, and column density $N_{12CO}$. Combining $I_{12CO}$ and $N_{12CO}$ data, we derive a global mass conversion law $N$=$N_{0}I^{p}$, where $N_{0}$$\approx$10$^{18}$mol/m$^{2}$ and $p$=2 at this resolution. We argue that the standard linear $N$=$XI$ is only approximately valid: $p$$\sim$1.5-1.0 at coarser resolutions or in atypical locations, such as Galactic Center clouds. Also, the velocity dispersion distributions are very different between $I_{12CO}$ and $N_{12CO}$, the former preferentially tracing more diffuse molecular gas. We re-evaluated Galactic rotation parameters for the 4Q, defining a new ``BGT'' model, and deprojected the (l,V) data onto (l,d) and (x,y) grids using standard kinematic procedures. To automate distance disambiguation inside the solar circle, we developed a simple $\zeta^{+}$ discriminator function and applied it to our deprojections. We discovered two previously unrecognised features of the molecular cloud population: widespread ripples in the midplane of wavelength 4kpc and amplitude 50pc, potentially generated by the last perigalactic passage of the Sgr dwarf; and three distant, massive molecular structures, the Far Ara clouds, two of which exhibit an exceptional velocity gradient, possibly lying in the far end of the Galaxy's Bar or a gas-rich dwarf galaxy $\sim$20-300 kpc beyond the disk

[74] arXiv:2503.21870 (替换) [中文pdf, pdf, html, 其他]

标题： 通过JWST强弱引力透镜分析的子弹星系团的高精度视图 显示英文标题

标题： A High-Caliber View of the Bullet Cluster Through JWST Strong and Weak Lensing Analyses

Sangjun Cha, Boseong Young Cho, Hyungjin Joo, Wonki Lee, Kim HyeongHan, Zachary P. Scofield, Kyle Finner, M. James Jee

评论： 11页，5图。发表于ApJL

期刊参考： 2025 天体物理期刊快报 987 L15

主题： 星系的天体物理学 (astro-ph.GA)

子弹星系团（1E 0657-56）是研究暗物质、星系团合并以及极端环境中冲击波传播的关键天体物理实验室。 利用新的JWST成像，我们展示了迄今为止最高分辨率的质量重建，结合了37个系统的146个强引力透镜约束和高密度（398个源每平方角分$^{-2}$）弱引力透镜数据，而无需假设光迹追踪质量。 主星系团的质量分布高度拉长（西北-东南方向），由至少三个与最亮星系团星系对齐的子团组成。 子团更紧凑，但沿东西方向拉长，具有一个主导峰值。 我们还检测到可能的质量和ICL尾迹，从子团的东侧延伸至主星系团。 值得注意的是，这些详细特征与星系团内光紧密跟踪，修改后的Hausdorff距离为$19.80 \pm 12.46$公里。 结合多波段数据，复杂的质量分布表明子弹星系团的合并历史可能比之前的双星系团合并情景更为复杂。 显示英文摘要

The Bullet Cluster (1E 0657-56) is a key astrophysical laboratory for studying dark matter, galaxy cluster mergers, and shock propagation in extreme environments. Using new JWST imaging, we present the highest-resolution mass reconstruction to date, combining 146 strong lensing constraints from 37 systems with high-density (398 sources arcmin$^{-2}$) weak lensing data, without assuming that light traces mass. The main cluster's mass distribution is highly elongated (NW-SE) and consists of at least three subclumps aligned with the brightest cluster galaxies. The subcluster is more compact but elongated along the E-W direction, with a single dominant peak. We also detect a possible mass and ICL trail extending from the subcluster's eastern side toward the main cluster. Notably, these detailed features are closely traced by the intracluster light, with a modified Hausdorff distance of $19.80 \pm 12.46$ kpc. Together with multi-wavelength data, the complex mass distribution suggests that the merger history of the Bullet Cluster may be more complex than previous binary cluster merger scenarios.

[75] arXiv:2504.02930 (替换) [中文pdf, pdf, html, 其他]

标题： 描述IllustrisTNG中非普遍的星系并合时标：主晕质量、重子物质和样本选择的影响 显示英文标题

标题： Describing the Nonuniversal Galaxy Merger Timescales in IllustrisTNG: Effects of Host Halo Mass, Baryons, and Sample Selection

Kun Xu (U Penn), Y.P. Jing (SJTU, TDLI)

评论： 21页，17图。已接受发表于ApJ。模型总结见表1

期刊参考： 天体物理学杂志，第986卷，2025年，第2期

主题： 星系的天体物理学 (astro-ph.GA) ; 宇宙学与非星系天体物理学 (astro-ph.CO)

星系合并时间尺度对于理解并模拟我们分层结构的宇宙中的星系形成至关重要。然而，先前的研究报告称，合并时间尺度在首次穿过$r_{\rm vir}$时对初始轨道参数和质量比的依赖性存在广泛差异。使用 IllustrisTNG 模拟，我们发现这些依赖性随着主机晕的质量而变化，这表明之前研究中的差异可能源于所分析系统的不同。具体来说，在低质量晕中，合并时间尺度对初始轨道参数的依赖性更强，而在高质量晕中，这种依赖性则减弱。为了考虑这些变化，我们提出了一种包含主机质量依赖性的拟合公式，实现了小于 0.15 dex 的对数散射。比较暗物质仅模拟和重子模拟，我们观察到对于圆形轨道的合并时间尺度相似，但对于径向轨道则有显著差异。在具有$M_{\rm{host}} < 10^{12.5} h^{-1} M_{\odot}$的晕中，暗物质仅模拟中的合并时间比重子模拟更长，而在更高质量的晕中，趋势则相反。我们将这些差异归因于中心星系盘的潮汐破坏作用和重子卫星对潮汐剥离的阻力之间的竞争效应。最后，我们将模型扩展为从晕内的任何起始半径预测合并时间尺度。通过将扩展模型拟合到整个吸积样本，我们发现仅使用合并样本可能会低估合并时间尺度，尤其是在低质量比的情况下。我们的模型为改进星系形成的半解析和经验模型提供了一个有价值的工具。 显示英文摘要

Galaxy merger timescales are crucial for understanding and modeling galaxy formation in our hierarchically structured Universe. However, previous studies have reported widely varying dependencies of merger timescales on initial orbital parameters and mass ratio at the first crossing of $r_{\rm vir}$. Using IllustrisTNG simulations, we find that these dependencies vary with host halo mass, suggesting that discrepancies in prior studies may arise from differences in the systems analyzed. Specifically, in low-mass halos, merger timescales show a stronger dependence on initial orbital parameters, while in high-mass halos, this dependence weakens. To account for these variations, we present a fitting formula that incorporates host mass dependence, achieving a logarithmic scatter smaller than 0.15 dex. Comparing dark matter-only and baryonic simulations, we observe similar merger timescales for circular orbits but notable differences for radial orbits. In halos with $M_{\rm{host}} < 10^{12.5} h^{-1} M_{\odot}$, mergers in dark matter-only runs take longer than in baryonic runs, whereas the trend reverses in more massive halos. We attribute these differences to the competing effects of tidal disruption by central galaxy disks and the resistance of baryonic satellites to tidal stripping. Finally, we extend our model to predict merger timescales from any starting radius within the halo. By fitting the extended model to the entire infall sample, we find that using only the merger sample can underestimate merger timescales, particularly for low mass ratios. Our model provides a valuable tool for improving semi-analytical and empirical models of galaxy formation.

[76] arXiv:2504.10241 (替换) [中文pdf, pdf, html, 其他]

标题： X射线星系团与一般星系群体之间的交叉相关性 显示英文标题

标题： Cross-correlations between X-ray clusters and the general galaxy population

Johan Comparat, Juan Macias-Perez, Céline Combet, Andrea Merloni, Dominique Eckert, Mohammadreza Ayromlou, Kirpal Nandra, Riccardo Seppi

评论： 已被A&A接收，数据可在 https://zenodo.org/records/15806800 获取

主题： 星系的天体物理学 (astro-ph.GA) ; 宇宙学与非星系天体物理学 (astro-ph.CO)

本研究提出了对DESILegacy调查目录中体积限制的星系样本与eROSITA选定的X射线星系团之间的交叉相关性的高精度测量，使得在红移和颜色方面进行详细分析成为可能。 两个关键发现浮现。 首先，将星系团-星系交叉相关性按安静星系和恒星形成星系分开时，包含了关于大质量环境中蓝云星系的吸积、反馈和抑制过程的重要信息。 这些结果与现有针对更高恒星质量的星系演化模型相符（$\log_{10}(M^*[M_\odot]) > 10.75$），尽管在中等质量范围内红色星系的比例可能略有低估（$10.25 < \log_{10}(M^*[M_\odot])< 10.75$）。 其次，在500 kpc范围内的交叉相关性的积分可以实现对星系团红色序列及其离散度的无模型测量，提供了一种稳健的替代方法，用于现有的红色序列校准方法，而无需光谱红移或星系分类。 对Euclid和LSST等未来的测光调查以及4MOST和DESI等光谱样本进行类似的分析应能显著提高信噪比，尤其是在小分离处。 显示英文摘要

This study presents highly precise measurements of the cross-correlation between volume-limited galaxy samples from the DESI legacy survey catalogue and X-ray selected galaxy clusters from eROSITA, allowing for detailed analysis across redshift and color. Two key findings emerge. First, the cluster-galaxy cross-correlation, when split into quiescent and star-forming galaxies, contains significant information about the infall, feedback, and quenching processes of blue cloud galaxies in massive environments. These results align well with existing galaxy evolution models for higher stellar masses ($\log_{10}(M^*[M_\odot]) > 10.75$), though the red fraction may be slightly underestimated in the intermediate mass range ($10.25 < \log_{10}(M^*[M_\odot])< 10.75$). Second, the integral of the cross-correlation within 500 kpc enables a model-independent measurement of the red sequence and its scatter in clusters, providing a robust alternative to existing red-sequence calibration methods without requiring spectroscopic redshifts or classifications of galaxies. Similar analyses on upcoming photometric surveys like Euclid and LSST and spectroscopic samples like 4MOST and DESI should lead to a significant increase in the signal-to-noise ratio, particularly at small separations.

[77] arXiv:2504.20857 (替换) [中文pdf, pdf, 其他]

标题： MIGHTEE-HI：具有解析恒星质量测量的径向加速度关系 显示英文标题

标题： MIGHTEE-HI: The radial acceleration relation with resolved stellar mass measurements

Andreea A. Vărăşteanu, Matt J. Jarvis, Anastasia A. Ponomareva, Harry Desmond, Ian Heywood, Tariq Yasin, Natasha Maddox, Marcin Glowacki, Michalina Maksymowicz-Maciata, Pavel E. Mancera Piña, Hengxing Pan

评论： 已被MNRAS接收发表，30页，19图（附录中还有21图）

主题： 星系的天体物理学 (astro-ph.GA) ; 宇宙学与非星系天体物理学 (astro-ph.CO)

径向加速度关系（RAR）是一种基本关系，通过将从动力学中得出的观测加速度与从重子质量估计的加速度相联系，将星系中的重子物质和暗物质联系起来。 这一关系表现出较小的离散性，因此为星系形成和演化的模型提供了关键约束——使我们能够绘制星系中暗物质的分布——以及修改动力学的模型。 然而，它仅在非常局部的宇宙中被广泛研究，且样本大多不一致。 我们提出了一种新的RAR测量方法，利用一个同质样本的19个HI选择的星系，直到$z=0.08$。 我们引入了一种新颖的方法，使用光谱能量分布（SED）拟合跨10个光度波段来测量分辨的恒星质量，以确定分辨的质量-光度比，我们证明这对于测量低加速度区域中重子物质产生的加速度是必不可少的。 我们的结果揭示了一个紧密的RAR，其低加速度幂律斜率为$\sim 0.5$，与之前的研究一致。 采用空间变化的质量-光度比可得到最紧密的RAR，其固有离散度仅为$0.045 \pm 0.022$兆，突显了分辨恒星质量测量在准确表征低质量、气体丰富的星系中重子物质引力贡献的重要性。 我们还发现了加速尺度红移演化的初步证据，但需要更多数据来确认这一点。 采用更一般的MOND插值函数，我们发现我们的结果缓解了先前RAR分析、太阳系四极矩和宽双星测试之间的紧张关系。 显示英文摘要

The radial acceleration relation (RAR) is a fundamental relation linking baryonic and dark matter in galaxies by relating the observed acceleration derived from dynamics to the one estimated from the baryonic mass. This relation exhibits small scatter, thus providing key constraints for models of galaxy formation and evolution -- allowing us to map the distribution of dark matter in galaxies -- as well as models of modified dynamics. However, it has only been extensively studied in the very local Universe with largely heterogeneous samples. We present a new measurement of the RAR, utilising a homogeneous sample of 19 HI-selected galaxies out to $z=0.08$. We introduce a novel approach of measuring resolved stellar masses using spectral energy distribution (SED) fitting across 10 photometric bands to determine the resolved mass-to-light ratio, which we show is essential for measuring the acceleration due to baryons in the low-acceleration regime. Our results reveal a tight RAR with a low-acceleration power-law slope of $\sim 0.5$, consistent with previous studies. Adopting a spatially varying mass-to-light ratio yields the tightest RAR with an intrinsic scatter of only $0.045 \pm 0.022$ dex, highlighting the importance of resolved stellar mass measurements in accurately characterising the gravitational contribution of the baryons in low-mass, gas-rich galaxies. We also find the first tentative evidence for redshift evolution in the acceleration scale, but more data will be required to confirm this. Adopting a more general MOND interpolating function, we find that our results ameliorate the tension between previous RAR analyses, the Solar System quadrupole and wide-binary test.

[78] arXiv:2504.21091 (替换) [中文pdf, pdf, html, 其他]

标题： 一个新的高纬度中性氢云复合体被包含在北天费米气泡中 显示英文标题

标题： A New High-latitude H I Cloud Complex Entrained in the Northern Fermi Bubble

Rongmon Bordoloi, Andrew J. Fox, Felix J. Lockman

评论： 天体物理期刊快报，4幅图，1张表

主题： 星系的天体物理学 (astro-ph.GA)

我们报告发现了11个高速HI云，在银河系纬度25-30度范围内，可能嵌入在银河系核风中。 这些云通过深空绿岸望远镜21厘米观测一个围绕类星体1H1613-097的$3.2^\circ \times 6.2^\circ$区域检测到，该区域位于北侧费米气泡之后。 我们的测量达到了$3\sigma$对$ N_{\mathrm{HI}}$的极限，低至$3.1 \times 10^{17}$cm$^{-2}$，比以前对气泡的HI研究灵敏度高两倍以上。 这些云的速度跨度为$-180 \leq v_{\mathrm{LSR}} \leq -90$km/s，是迄今为止在气泡内部检测到的最高纬度的21厘米HVCs。 八个云团在空间上被解析，显示出大小为4-28 pc的相干结构，峰值柱密度为$\log(N_{\mathrm{HI}}/\mathrm{cm}^2) = 17.9\text{-}18.7$，HI质量高达 1470 $M_\odot$。 几个云团表现出内部速度梯度。 考虑到从银河系中心被驱逐的云团预期生存时间较短，这些云团出现在如此高的纬度令人意外。 这些物体可能是更大云团的碎片，由于与周围热气体的相互作用而被破坏。 显示英文摘要

We report the discovery of eleven high-velocity HI clouds at Galactic latitudes of 25-30 degrees, likely embedded in the Milky Way's nuclear wind. The clouds are detected with deep Green Bank Telescope 21 cm observations of a $3.2^\circ \times 6.2^\circ$ field around QSO 1H1613-097, located behind the northern Fermi Bubble. Our measurements reach $3\sigma$ limits on $ N_{\mathrm{HI}}$ as low as $3.1 \times 10^{17}$ cm$^{-2}$, more than twice as sensitive as previous HI studies of the Bubbles. The clouds span $-180 \leq v_{\mathrm{LSR}} \leq -90$ km/s and are the highest-latitude 21 cm HVCs detected inside the Bubbles. Eight clouds are spatially resolved, showing coherent structures with sizes of 4-28 pc, peak column densities of $\log(N_{\mathrm{HI}}/\mathrm{cm}^2) = 17.9\text{-}18.7$, and HI masses up to 1470 $M_\odot$. Several exhibit internal velocity gradients. Their presence at such high latitudes is surprising, given the short expected survival times for clouds expelled from the Galactic Center. These objects may be fragments of a larger cloud disrupted by interaction with the surrounding hot gas.

[79] arXiv:2506.08751 (替换) [中文pdf, pdf, html, 其他]

标题： XRISM对星际硫的见解 显示英文标题

标题： XRISM insights for interstellar Sulfur

Lia Corrales, Elisa Costantini, Sascha Zeegers, Liyi Gu, Hiromitsu Takahashi, David Moutard, Megumi Shidatsu, Jon M. Miller, Misaki Mizumoto, Randall K. Smith, Ralf Ballhausen, Priyanka Chakraborty, Marua Diaz Trigo, Renee Ludlam, Takao Nakagawa, Ioanna Psaradaki, Shinya Yamada, Caroline A. Kilbourne

评论： 已接受发表于PASJ

主题： 星系的天体物理学 (astro-ph.GA) ; 高能天体物理现象 (astro-ph.HE)

X射线成像光谱任务（XRISM）提供了最佳的光谱分辨率，以研究来自星际介质（ISM）的硫（S）K壳层光吸收特征。 我们首次展示了在X射线双星（XRBs）4U 1630-472和GX 340+0的光谱中检测到星际原子SII K-beta吸收的高信号。 这一特征在多个仪器、目标和流量状态下持续存在，表明其具有星际性质。 在考虑系统不确定性后，我们测得SII Kbeta线中心位于2470.8 +/- 1.1 eV。 我们还发现，最近发表的高分辨率SII吸收模板需要一个+7-8 eV的系统能量刻度偏移，这与各种原子建模程序之间的不一致水平相当。 XRISM对GX 340+0的300 ks观测在S K区域提供了前所未有的信噪比，我们在GX 340+0的光谱中发现了固体S的残留吸收。 三种铁-硫化合物的吸收模板，即陨铁矿（FeS）、磁黄铁矿（Fe_7S_8）和黄铁矿（FeS_2），对残留部分提供了同样好的拟合。 尽管我们无法区分这三种化合物，但它们对尘埃颗粒中硫的丰度估计是相同的。 考虑到GX 340+0视线中的气态和固态硫，使我们能够直接测量硫的耗竭，其值为40% +/- 15%。 我们的耗竭测量为星际铁结合在Fe-S化合物中的比例提供了一个上限，小于25%，这与通过铁L壳层吸收对Fe-S化合物的先前研究一致。 本研究中的两个XRB距离约为11 kpc，并位于银河盘的另一侧，表明该值可能代表银河系中所有星际介质相位平均的硫耗竭。 显示英文摘要

The X-ray Imaging Spectroscopy Mission (XRISM) provides the best spectral resolution with which to study Sulfur (S) K-shell photoabsorption features from the interstellar medium (ISM). For the first time, we demonstrate the high-signal detection of interstellar atomic SII K-beta absorption in the spectrum of X-ray binaries (XRBs) 4U 1630-472 and GX 340+0. The persistence of this feature across multiple instruments, targets, and flux states implies that it is interstellar in nature. We measure the SII Kbeta line centroid at 2470.8 +/- 1.1 eV after including systematic uncertainties. We also find that the most recently published high resolution SII absorption template requires a systematic energy scale shift of +7-8 eV, which is comparable to the level of disagreement among various atomic modeling procedures. The XRISM 300 ks observation of GX 340+0 provides unprecedented signal-to-noise in the S K region, and we find evidence of residual absorption from solid S in the spectra of GX 340+0. Absorption templates from three Fe-S compounds, troilite (FeS), pyrrhotite (Fe_7S_8) and pyrite (FeS_2), provide equally good fits to the residuals. Even though we are not able to distinguish among these three compounds, they provide equal estimates for the abundance of S locked in dust grains. Having accounted for both the gaseous and solid S in the GX 340+0 sightline provides us with a direct measurement of S depletion, which is 40% +/- 15%. Our depletion measurement provides an upper limit to the fraction of interstellar Fe bound in Fe-S compounds of < 25%, which is consistent with prior studies of Fe-S compounds via Fe L-shell absorption. Both XRBs in this study are at a distance of approximately 11 kpc and on the opposite side of the Galactic disk, suggesting that this value could represent the average S depletion of the Milky Way when integrated across all phases of the ISM.

[80] arXiv:2506.15268 (替换) [中文pdf, pdf, html, 其他]

标题： AVID：室女座星系团边缘的晚型矮星系（VCC 479）合并主要合并的形成与演化 显示英文标题

标题： AVID: Formation and evolution of a coalesced major merger of late-type dwarf galaxies (VCC 479) on the outskirts of the Virgo cluster

Weibin Sun, Hong-Xin Zhang, Rory Smith, Elias Brinks, Patrick Côté, Se-Heon Oh, Zesen Lin, Alessandro Boselli, Laura Ferrarese, Fujia Li, Yuzhu Sun, Lijun Chen, Lanyue Zhang, Minsu Kim, Jaebeom Kim, Tie Li, Bojun Tao, Matt Taylor, Pierre-Alain Duc, Ruben Sánchez-Janssén, Yinghe Zhao, Sanjaya Paudel, Eric W. Peng, Kaixiang Wang, Stephen Gwyn, Matteo Fossati, Jean-Charles Cuillandre

评论： 18页，15图。已接受发表于A&A

主题： 星系的天体物理学 (astro-ph.GA)

矮星系与矮星系的合并是矮星系在进入星系团前处理中最少被探索的方面之一。 我们介绍了第一个关于一个合并的晚期型矮星主要合并体（VCC 479；恒星质量$\sim\,8\,\times\,10^7\,\rm M_\odot$）的案例研究，该合并体经历了显著的环境影响，旨在探讨星系相互作用和环境过程共同作用下的矮星系演化，并理解其在星系团环境中矮星系多样性的相关性。 我们的分析基于原子气体在室女座相互作用矮星系（AVID）调查中的VLA和FAST HI发射线映射。 我们还对矮星系-矮星系合并进行了理想化的流体动力学模拟，以帮助解释观测结果。 我们在VCC 479中识别出对称的恒星壳状结构，表明发生了矮星系的主要合并。 该星系有一个中心恒星爆发，始于$\sim$600 Myr 前，嵌入在一个在$\sim$1 Gyr 前被抑制的指数盘中。 恒星爆发仅贡献了总恒星质量的 2.9$\pm$0.5%，并且VCC 479的整体恒星形成率比类似质量的典型矮星低0.3 dex。 该星系的HI缺乏严重，大部分HI气体集中在中心1 kpc内，几乎没有扩展的HI包层。 HI速度场与恒星主体的不对齐最好由合并触发的气体流入来解释，这在我们的模拟中可以看到。 我们的分析与这样一个情景一致：在最终合并之前，星系团环境已经移除了前身星系的大部分HI气体。 合并将剩余的气体集中到星系中心，触发了中心恒星爆发。 环境剥离和星系合并的综合效应使VCC 479转变为一个蓝核矮星，正在经历从晚型星系向早型星系的形态转变。 显示英文摘要

Dwarf-dwarf galaxy mergers are among the least explored aspects of dwarf galaxy pre-processing as they fall into clusters. We present the first case study of a coalesced late-type dwarf major merger (VCC 479; stellar mass $\sim\,8\,\times\,10^7\,\rm M_\odot$) that has undergone significant environmental influence, with the aim of exploring dwarf galaxy evolution under the combined effects of galaxy interactions and environmental processes, and understanding its relevance to the diversity of dwarf galaxies in cluster environments. Our analysis is based on VLA and FAST HI emission line mapping from the Atomic gas in Virgo Interacting Dwarf galaxies (AVID) survey. We also perform idealized hydrodynamical simulations of dwarf-dwarf mergers to help interpret the observations. We identify symmetric stellar shell structures in VCC 479, indicative of a coalesced major merger of dwarf galaxies. The galaxy features a central starburst, initiated $\sim$600 Myr ago, embedded within an exponential disk quenched $\sim$1 Gyr ago. The starburst contributes only 2.9$\pm$0.5\% of the total stellar mass, and VCC 479's global star formation rate is 0.3 dex lower than typical dwarfs of similar mass. The galaxy is highly HI deficient, with most HI gas concentrated within the central 1 kpc and little extended HI envelope. The misalignment of the HI velocity field with the stellar body is best explained by merger-triggered gas inflow, as seen in our simulations. Our analysis is consistent with a scenario that the majority of HI gas of the progenitor galaxies was removed by the cluster environment prior to the final coalescence. The merger concentrates the remaining gas toward the galaxy center, triggering a central starburst. The combined effect of environment stripping and galaxy merger has transformed VCC 479 into a blue-core dwarf undergoing morphological transition from a late-type to an early-type galaxy.

[81] arXiv:2507.00770 (替换) [中文pdf, pdf, html, 其他]

标题： 银河系暗物质模型的微透镜效应 显示英文标题

标题： Microlensing of dark matter models in the Milky Way

Bichu Li, Chan-Yu Tang, Zhuo-Ran Huang, Lei-Hua Liu

评论： 25页，8图，

主题： 星系的天体物理学 (astro-ph.GA) ; 宇宙学与非星系天体物理学 (astro-ph.CO)

我们利用来自OGLE巡天观测的五年微透镜数据，研究了作为暗物质（DM）候选体的原始黑洞（PBH）丰度的限制条件。 虽然OGLE观测到的大约2000年左右的大多数微透镜事件可以通过褐矮星、主序星和致密遗迹等恒星种群很好地解释，但六个超短时间尺度事件（大约0.1 - 0.3天）可能预示着PBH的存在。 在先前采用Navarro-Frenk-White (NFW)暗物质轮廓线的研究基础上，我们研究了其他暗物质晕模型——特别是Einasto和Burkert轮廓线——如何影响微透镜效应预测以及PBH丰度的限制条件。 我们以主序星事件率作为观测基准，计算了这两个轮廓线的微透镜事件率差值。 我们的结果表明，Einasto 和 Burkert 轮廓均未重现主序恒星事件的分布，但两者均可对超黑洞质量 $M_{\mathrm{PBH}} \sim 10^{-5} M_\odot$ 的超短时间尺度事件提供可行的解释。 在 OGLE 数据集中未观测到任何超黑洞的零假设下，使用泊松似然分析，我们推导出 $f_{\mathrm{PBH}}$ 的 95% CL 上限，发现与 NFW 情况相比，Einasto 和 Burkert 轮廓下的约束明显放宽。 这些结果强调了超黑洞约束对假设的暗物质晕结构的敏感性，并强调了准确模拟银河系内密度轮廓对于稳健评估超黑洞暗物质情景的重要性。 显示英文摘要

We investigate constraints on the abundance of primordial black holes (PBHs) as dark matter (DM) candidates using five years of microlensing data from the OGLE survey. While the majority of OGLE's $\sim 2000$ microlensing events are well-explained by stellar populations such as brown dwarfs, main-sequence stars, and compact remnants, a subset of six ultrashort-timescale events ($t_E \sim 0.1 - 0.3$ days) may signal the presence of PBHs. Building upon prior work that adopted the Navarro-Frenk-White (NFW) DM profile, we examine how alternative DM halo models -- specifically the Einasto and Burkert profiles -- affect microlensing predictions and the constraints on PBH abundance. We computed differential microlensing event rates for both profiles, using the main-sequence star rate as an observational benchmark. Our results show that neither the Einasto nor Burkert profiles reproduce the distribution of main-sequence star events, yet both allow for viable explanations of the ultrashort-timescale events with PBH masses $M_{\mathrm{PBH}} \sim 10^{-5} M_\odot$. Using a Poisson likelihood analysis under the null hypothesis that no PBH is observed in OGLE dataset, we derive 95\% C.L. upper bounds on $f_{\mathrm{PBH}}$, finding that the constraints are significantly relaxed under the Einasto and Burkert profiles compared to the NFW case. These results underscore the sensitivity of PBH constraints to the assumed DM halo structure and highlight the importance of accurately modeling the inner Galactic density profile to robustly assess PBH dark matter scenarios.

[82] arXiv:2507.01092 (替换) [中文pdf, pdf, html, 其他]

标题： IllustrisTNG50中星系合并中的恒星形成和黑洞吸积率增强 显示英文标题

标题： Enhanced Star Formation and Black Hole Accretion Rates in Galaxy Mergers in IllustrisTNG50

Aimee L. Schechter, Shy Genel, Bryan Terrazas, Julia M. Comerford, Abigail Hartley, Rachel S. Somerville, Rebecca Nevin, Joseph Simon, Erica Nelson

评论： 21页，11图，已被天体物理学杂志接受

主题： 星系的天体物理学 (astro-ph.GA)

许多理论和观测研究认为，星系合并可能会触发增强的恒星形成或活动星系核（AGN）活动。 我们对IllustrisTNG50模拟中的$0.2 \leq z \leq 3$进行了合并和非合并星系的分析。 这些星系涵盖了多种质量（$M_\star > 10^{8}M_\odot$）、多个合并阶段以及质量比（$\geq1:10$）。 我们研究了星系合并对TNG50宇宙中恒星形成率和黑洞吸积率的影响。 我们还进一步探讨了星系和黑洞质量、合并阶段、合并质量比以及红移如何影响这些数值。 我们样本中的合并显示出在$z \leq 3$时恒星形成率的特异性（sSFR）过高，以及在$z \lesssim 2$时黑洞吸积率的特异性（sBHAR）增强。 与非合并样本相比，合并样本中的sSFR和sBHAR之间的差异随着红移的降低而增加。 此外，我们证明这些增强效应至少在合并事件后$\sim1$Gyr内仍然存在。 研究TNG50模拟中合并行为在宇宙时间中的表现，有助于更好地理解空间分辨率在宇宙学模拟中的重要性，并为更好地理解我们高-$z$宇宙提供了更好的基础，这些观测来自$\textit{JWST}$。 显示英文摘要

Many theoretical and observational studies have suggested that galaxy mergers may trigger enhanced star formation or active galactic nuclei (AGN) activity. We present an analysis of merging and nonmerging galaxies from $0.2 \leq z \leq 3$ in the IllustrisTNG50 simulation. These galaxies encompass a range of masses ($M_\star > 10^{8}M_\odot$), multiple merger stages, and mass ratios ($\geq1:10$). We examine the effect that galaxy mergers have on star formation and black hole accretion rates in the TNG50 universe. We additionally investigate how galaxy and black hole mass, merger stage, merger mass ratio, and redshift affect these quantities. Mergers in our sample show excess specific star formation rates (sSFR) at $z \leq 3$ and enhanced specific black hole accretion rates (sBHAR) at $z \lesssim 2$. The difference between sSFRs and sBHARs in the merging sample compared to the non-merging sample increases as redshift decreases. Additionally, we show that these enhancements persist for at least $\sim1$ Gyr after the merger event. Investigating how mergers behave in the TNG50 simulation throughout cosmic time enables both a better appreciation of the importance of spatial resolution in cosmological simulations and a better basis to understand our high-$z$ universe with observations from $\textit{JWST}$.

[83] arXiv:2409.16079 (替换) [中文pdf, pdf, html, 其他]

标题： 评估纯暗物质模拟中神经网络预测的星系形成历史 显示英文标题

标题： Evaluating the galaxy formation histories predicted by a neural network in pure dark matter simulations

Harry George Chittenden, Jayashree Behera, Rita Tojeiro

评论： 23页，19图，已接受发表于MNRAS，同时发表的还有配套论文：arXiv:2409.16548

主题： 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA)

我们研究了一系列利用暗物质仅模拟中的合并树和环境历史计算的星系属性，使用半递归神经网络生成星系演化的自洽预测，并基于类似预测的傅里叶变换对模型进行随机改进。 我们将这些方法应用于IllustrisTNG模拟的暗物质仅运行，以了解重子物质移除的影响，以及应用于千秒差距体积的纯暗物质模拟Uchuu，以了解低分辨率或替代晕属性度量的影响。 我们发现机器学习模型能够恢复从预测的恒星形成和恒星金属丰度历史中得出的准确总结统计量，以及相应的光谱和测光数据。 然而，该模型在暗物质模拟上的应用存在显著的不准确性，特别是在低质量和缓慢增长的晕中。 对于这些物体，由于缺乏恒星反馈，晕质量增长速率被夸大，但在低分辨率模拟中，由于缺乏低质量前体，晕的形成可能受到严重限制。 此外，高质量晕的结构和环境差异导致红色熄灭星系的过量出现。 这些结果标志着朝着基于星系-晕联系的物理解释构建高保真模拟的机器学习模型取得了进展，但它们也说明了需要考虑晕属性和模拟分辨率的差异。 显示英文摘要

We investigate a series of galaxy properties computed using the merger trees and environmental histories from dark matter only cosmological simulations, using a semi-recurrent neural network producing self-consistent predictions of galaxy evolution, and using stochastic improvements to this model based on similarly predicted Fourier Transforms. We apply these methods to the dark matter only runs of the IllustrisTNG simulations to understand the effects of baryon removal, and to the gigaparsec-volume pure dark matter simulation Uchuu, to understand the effects of the lower resolution or alternative metrics for halo properties. We find that the machine learning model recovers accurate summary statistics derived from the predicted star formation and stellar metallicity histories, and correspondent spectroscopy and photometry. However, the inaccuracies of the model's application to dark simulations are substantial for low mass and slowly growing haloes. For these objects, the halo mass accretion rate is exaggerated due to the lack of stellar feedback, yet the formation of the halo can be severely limited by the absence of low mass progenitors in a low resolution simulation. Furthermore, differences in the structure and environment of higher mass haloes results in an overabundance of red, quenched galaxies. These results signify progress towards a machine learning model which builds high fidelity mocks based on a physical interpretation of the galaxy-halo connection, yet they illustrate the need to account for differences in halo properties and the resolution of the simulation.

[84] arXiv:2501.03738 (替换) [中文pdf, pdf, html, 其他]

标题： 探索NGC 7419的成员和变异性：一个富含超巨星和Be型恒星的开放星团 显示英文标题

标题： Exploring membership and variability in NGC 7419: An open cluster rich in super giants and Be type stars

Arghya Chakraborty, Jessy Jose, Alex C. Carciofi

主题： 太阳与恒星天体物理学 (astro-ph.SR) ; 星系的天体物理学 (astro-ph.GA)

NGC 7419是一个年轻的开放星团，以其拥有五颗红超巨星和大量经典Be（CBe）恒星而著称。 CBe恒星是主序非超巨星B型恒星，其光谱中表现出或曾表现出巴尔末线发射。 我们使用盖亚DR3数据和机器学习技术如高斯混合模型（GMM）和随机森林（RF）进行成员分析，并确定该星团的平均距离为${3.6^{+1.0}_{-0.6}}$kpc。 我们识别出499个基于盖亚的成员，其质量高于$\sim$1.2 M$_\odot$，并估计该星团的年龄为$21.1 ^{+1.6}_{-0.6}$Myr。 通过我们修订后的基于过量的$H\alpha$分析，我们发现了42个CBe恒星，其中包含许多已知的CBe恒星，使NGC 7419中的CBe恒星总数达到49个，CBe恒星占（B+CBe）成员的比例为12.7%。 我们利用ZTF和NEOWISE数据研究候选成员的变异性，使用标准差、中位数绝对偏差和Stetson指数（J），并使用广义 Lomb-Scargle 周期图研究其周期性。 我们发现66%的CBe恒星具有变异性：23%显示典型的脉动/自转周期信号，41%表现出与盘动力学或双星相关的变异性特征，14%表现出长期变化，这与盘的消散/形成一致。 我们还发现所有脉动的CBe恒星都是早型，而50%具有长期变化的恒星是早型，其余50%是中型。 我们的结果与文献中的先前发现一致，并确认CBe恒星在不同时间尺度上通过多种机制表现出变异性。 显示英文摘要

NGC 7419 is a young open cluster notable for hosting five Red Supergiants and a high abundance of Classical Be (CBe) stars. CBe stars are main sequence non-supergiant B-type stars, which exhibit or have exhibited Balmer line emissions in their spectra. We perform a membership analysis using Gaia DR3 data and machine learning techniques like Gaussian Mixture Models (GMM) and Random Forest (RF) and determine the cluster's mean distance to be ${3.6^{+1.0}_{-0.6}}$ kpc. We identify 499 Gaia-based members with a mass above $\sim$ 1.2 M$_\odot$, and estimate the cluster's age to be $21.1 ^{+1.6}_{-0.6}$ Myr. Using our revised $H\alpha$ excess-based analysis, we find 42 CBe stars containing many known CBe stars, bringing the total number of CBe stars in NGC 7419 to 49 and the fraction of CBe to (B+CBe) members to 12.7%. We investigate the variability of the candidate members from ZTF and NEOWISE data using Standard Deviation, Median Absolute Deviation, and Stetson Index (J), and their periodicity using the Generalized Lomb Scargle Periodogram variability. We find that 66% of CBe stars are variable: 23% show periodic signals, typical of pulsation/rotation, 41% display variability characteristic of disk dynamics or binarity, and 14% exhibit long-term changes, consistent with disk dissipation/formation. We also find that all pulsating CBe stars are early-type, while 50% of stars with long-term variations are early-type, and the other 50% are mid-type. Our results agree with previous findings in the literature and confirm that CBe stars display variability through multiple mechanisms across different timescales.

[85] arXiv:2503.07733 (替换) [中文pdf, pdf, html, 其他]

标题： HOLISMOKES XVI：在HSC-PDR3中使用神经网络委员会进行透镜搜索以及用于去除假阳性的后处理 显示英文标题

标题： HOLISMOKES XVI: Lens search in HSC-PDR3 with a neural network committee and post-processing for false-positive removal

S. Schuldt, R. Cañameras, Y. Shu, I. T. Andika, S. Bag, C. Grillo, A. Melo, S. H. Suyu, S. Taubenberger

评论： 10+9页，7+7图，已被A&A接收

主题： 天体物理学的仪器与方法 (astro-ph.IM) ; 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA)

我们已经进行了系统的星系尺度透镜搜索，利用了Hyper Suprime-Cam（HSC）调查第三次公开数据释放的多波段成像数据，重点在于移除假阳性，在对所有i-Kron半径大于0.8"的1.1亿个源应用深度学习分类器之后。为了提高性能，我们测试了之前透镜搜索项目中多个网络的组合，并发现通过平均我们五个网络的得分可以获得最佳性能。尽管这种集成网络在已知真实透镜上已经达到了75%真正阳性率（TPR）时0.01%的假阳性率（FPR），但我们已经详细制定了技术手段，在视觉检查之前进一步清理网络候选列表。具体来说，我们测试了使用SExtractor和HOLISMOKES IX中的建模网络进行拒绝，这一起作用导致候选拒绝率为29%，而不会降低TPR。我们进行了全面的多阶段视觉检查，涉及八个人，并识别出95个A级（平均等级G >2.5）和503个B级（2.5 >G >1.5）透镜候选者，包括92个首次报告的发现。这次检查还结合了一种新颖的环境特征分析，使用光度红移直方图。我们公开发布了所有经过视觉检查的候选者的平均等级、质量模型预测和环境特征，同时包含了先前发现系统的参考文献，这使得这个目录成为已知透镜的最大编目之一。结果表明，(1) 多个网络的组合提高了选择性能，(2) 自动遮罩工具以及建模网络，可以轻松应用于数十万个网络候选者，有助于减少假阳性数量，这是目前透镜搜索的主要限制。 显示英文摘要

We have carried out a systematic search for galaxy-scale lenses exploiting multi-band imaging data from the third public data release of the Hyper Suprime-Cam (HSC) survey with the focus on false-positive removal, after applying deep learning classifiers to all 110 million sources with i-Kron radius above 0.8". To improve the performance, we tested the combination of multiple networks from our previous lens search projects and found the best performance by averaging the scores from five of our networks. Although this ensemble network leads already to a false-positive rate (FPR) of 0.01% at a true-positive rate (TPR) of 75% on known real lenses, we have elaborated techniques to further clean the network candidate list before visual inspection. In detail, we tested the rejection using SExtractor and the modeling network from HOLISMOKES IX, which resulted together in a candidate rejection of 29% without lowering the TPR. We carried out a comprehensive multi-stage visual inspection involving eight individuals and identified 95 grade A (average grade G >2.5) and 503 grade B (2.5 >G >1.5) lens candidates, including 92 discoveries reported for the first time. This inspection also incorporated a novel environmental characterization using histograms of photometric redshifts. We publicly release the average grades, mass model predictions, and environment characterization of all visually inspected candidates, while including references for previously discovered systems, which makes this catalog one of the largest compilation of known lenses. The results demonstrate that (1) the combination of multiple networks enhances the selection performance and (2) both automated masking tools as well as modeling networks, which can be easily applied to hundreds of thousands of network candidates, help reduce the number of false positives that is the main limitation in lens search to date.

[86] arXiv:2503.19111 (替换) [中文pdf, pdf, html, 其他]

标题： 通过自监督学习对射电源进行分类 显示英文标题

标题： Classification of Radio Sources Through Self-Supervised Learning

Nicolas Baron Perez, Marcus Brüggen, Gregor Kasieczka, Luisa Lucie-Smith

主题： 天体物理学的仪器与方法 (astro-ph.IM) ; 星系的天体物理学 (astro-ph.GA)

射电星系的形态反映了它们与其他环境的相互作用，以及其他效应。 由于现代射电巡天包含了大量无法手动分析和分类的射电源，因此开发自动方案非常重要。 与其他受益于已建立的理论框架和模拟的领域不同，目前没有为射电星系构建这样的综合模型。 这给该领域的数据分析带来了挑战，需要新颖的方法。 在本研究中，我们利用自监督学习对LOFAR两米天空调查数据发布2（LoTSS-DR2）中的射电星系进行分类。 我们的深度聚类分类策略包括三个主要步骤：(i) 自监督预训练；(ii) 使用从学习到的表示中创建的标记子样本进行微调；以及 (iii) 对选定的未标记样本进行最终分类。 为了增强表示中的形态信息，我们开发了一种额外的随机增强方法，称为随机结构视图（RSV）。 我们的结果表明，学习到的表示包含丰富的形态信息，能够创建一个有效捕捉未标记样本内部形态多样性的标记子样本。 此外，将未标记样本分类为12个形态类别可以得到稳健的类别概率。 我们成功地证明了LoTSS-DR2中包含多种形态的射电星系子集可以通过基于自监督学习的深度聚类进行分类。 在此开发的方法填补了缺乏模拟和理论模型所留下的空白，提供了一个可以立即应用于其他波段天文学图像分析的框架。 显示英文摘要

The morphology of radio galaxies is indicative of their interaction with their surroundings, among other effects. Since modern radio surveys contain a large number of radio sources that would be impossible to analyse and classify manually, it is important to develop automatic schemes. Unlike other fields, which benefit from established theoretical frameworks and simulations, there are no such comprehensive models built for radio galaxies. This stands as a challenge to data analysis in this field and novel approaches are required. In this study, we investigate the classification of radio galaxies from the LOFAR Two-meter Sky Survey Data Release 2 (LoTSS-DR2) using self-supervised learning. Our deep clustering classification strategy involves three main steps: (i) self-supervised pre-training; (ii) fine-tuning using a labelled subsample created from the learned representations; and (iii) performing a final classification of the selected unlabelled sample. To enhance morphological information in the representations, we developed an additional random augmentation, called a random structural view (RSV). Our results demonstrate that the learned representations contain rich morphological information, enabling the creation of a labelled subsample that effectively captures the morphological diversity within the unlabelled sample. Additionally, the classification of the unlabelled sample into 12 morphological classes yields robust class probabilities. We successfully demonstrated that a subset of radio galaxies from LoTSS-DR2, encompassing diverse morphologies, can be classified using deep clustering based on self-supervised learning. The methodology developed here bridges the gap left by the absence of simulations and theoretical models, offering a framework that can readily be applied to astronomical image analyses in other bands.

[87] arXiv:2505.00553 (替换) [中文pdf, pdf, html, 其他]

标题： 刀刃法作为一种验证强透镜质量模型的新方法 显示英文标题

标题： The Jackknife method as a new approach to validate strong lens mass models

Shun Nishida, Masamune Oguri, Yoshinobu Fudamoto, Ayari Kitamura

评论： 14页，9图，发表于《天体物理学开放期刊》

主题： 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA)

在强引力透镜分析中，质量模型的准确性对于无偏预测诸如放大率和时间延迟等物理量至关重要。 虽然通过改变质量模型的参数来匹配多个像的预测位置与观测结果来优化质量模型，但通常需要提升多个像的位置不确定性以考虑透镜天体中暗物质的复杂结构，这使得对卡方值的解释变得困难。 我们引入自助法作为一种新方法来验证强引力透镜质量模型，特别关注于星系团尺度的质量建模。 在此方法中，我们从拟合中移除一个源的多个像，并使用剩余源的多个像来优化质量模型。 然后我们计算被移除源的多个像，并定量评估它们与观测位置的匹配程度。 我们发现，在使用简单模型的模拟中，自助法表现有效。 我们还通过星系团MACS J0647.7+7015的质量建模展示了我们的方法。 我们讨论了利用自助法验证马尔可夫链蒙特卡罗方法对物理量误差估计的潜力。 显示英文摘要

The accuracy of a mass model in the strong lensing analysis is crucial for unbiased predictions of physical quantities such as magnifications and time delays. While the mass model is optimized by changing parameters of the mass model to match predicted positions of multiple images with observations, positional uncertainties of multiple images often need to be boosted to take account of the complex structure of dark matter in lens objects, making the interpretation of the chi-square value difficult. We introduce the Jackknife method as a new method to validate strong lens mass models, specifically focusing on cluster-scale mass modeling. In this approach, we remove multiple images of a source from the fitting and optimize the mass model using multiple images of the remaining sources. We then calculate the multiple images of the removed source and quantitatively evaluate how well they match the observed positions. We find that the Jackknife method performs effectively in simulations using a simple model. We also demonstrate our method with mass modeling of the galaxy cluster MACS J0647.7+7015. We discuss the potential of using the Jackknife method to validate the error estimation of the physical quantities by the Markov Chain Monte Carlo.

[88] arXiv:2505.05675 (替换) [中文pdf, pdf, html, 其他]

标题： 熵平台可能从模拟的星系团和群中的特征晕质量处的气体替换中产生 显示英文标题

标题： Entropy plateaus can emerge from gas replacement at a characteristic halo mass in simulated groups and clusters of galaxies

Edoardo Altamura, Scott T. Kay, Joop Schaye, Ian G. McCarthy, Matthieu Schaller

评论： 22页，8张图，2张表。已接受发表于MNRAS。代码、数据和文档可在以下网址获取 https://github.com/edoaltamura/entropy-core-evolution

主题： 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA) ; 计算物理 (physics.comp-ph)

星系际介质（IGM）的演化受到引力坍缩、辐射冷却和重子反馈的影响。 使用宇宙学流体动力学放大模拟的一个 $8.83 \times 10^{12}$ M$_\odot$ 群和一个 $2.92 \times 10^{14}$ M$_\odot$ 密度在 $z=0$的团，我们研究了熵平台的出现及其与反馈机制的联系。 这个设置使用了SWIFT-EAGLE模型，具有三种分辨率，最低的初始粒子气体质量为$2.29 \times 10^5$M$_\odot$，暗物质为$1.23 \times 10^6$M$_\odot$。 我们发现，当晕团达到特征质量$\sim 10^{12}$M$_{\odot}$时，它们的熵剖面在virial半径处变平，标志着从超新星到活动星系核反馈驱动调节的转变。 随着晕团增长为星系团（$\sim 10^{13}$M$_{\odot}$），熵平台向内扩展，并在大质量系统中形成等熵核心（$\sim 10^{14}$M$_{\odot}$）。 通过跟踪气体粒子的拉格朗日历史，我们证明这种熵的积累主要由活动星系核反馈驱动，该过程有效地从星系团和群的前身中移除低熵气体，并在落入核心之前将其重新分布到星际介质中。 对X-GAP星系团的最新观测显示存在大的熵过剩和平台，这与我们的发现一致，与大多数先前观测的幂律型轮廓形成对比。 虽然熵平台和大的熵过剩可能在无偏样本中被观测确认，但再现熵分布的全部多样性仍然是下一代反馈模型的一个未解挑战。 我们的结果表明，当前的反馈模型可能在将低熵气体从潜在的冷核心前身中排出方面过于高效，从而破坏了维持持久冷核心所需的加热与冷却平衡。 显示英文摘要

The evolution of the intergalactic medium (IGM) is influenced by gravitational collapse, radiative cooling, and baryonic feedback. Using cosmological hydrodynamic zoom-in simulations of a $8.83 \times 10^{12}$ M$_\odot$ group and a $2.92 \times 10^{14}$ M$_\odot$ cluster at $z=0$, we investigate the emergence of entropy plateaus and their connection to feedback mechanisms. This set-up uses the SWIFT-EAGLE model with three resolutions, down to an initial particle gas mass of $2.29 \times 10^5$ M$_\odot$ and $1.23 \times 10^6$ M$_\odot$ for dark matter. We find that, when halos reach the characteristic mass of $\sim 10^{12}$ M$_{\odot}$, their entropy profiles flatten at the virial radius, marking a transition from supernova to AGN feedback-driven regulation. As halos grow into groups ($\sim 10^{13}$ M$_{\odot}$), the entropy plateau extends inward and isentropic cores form in massive systems ($\sim 10^{14}$ M$_{\odot}$). By tracking the Lagrangian history of gas particles, we demonstrate that this entropy buildup is primarily driven by AGN feedback, which efficiently removes low-entropy gas from progenitors of groups and clusters, redistributing it throughout the IGM before falling into the core. Recent observations of X-GAP groups reveal large entropy excesses and plateaus, in line with our findings and in contrast to the power-law-like profiles of most previous observations. While entropy plateaus and large entropy excesses may be observationally confirmed in unbiased samples, reproducing the full diversity of entropy profiles remains an outstanding challenge for next-generation feedback models. Our results suggest that current feedback models may be overly efficient in expelling low-entropy gas from the potential cool-core progenitors, disrupting the balance between heating and cooling required for long-lived cool cores.

[89] arXiv:2506.06269 (替换) [中文pdf, pdf, html, 其他]

标题： 精确模拟核心坍缩自相互作用暗物质晕 显示英文标题

标题： Accurately simulating core-collapse self-interacting dark matter halos

Moritz S. Fischer, Hai-Bo Yu, Klaus Dolag

评论： 13页，16图+附录

主题： 宇宙学与非星系天体物理学 (astro-ph.CO) ; 星系的天体物理学 (astro-ph.GA) ; 高能物理 - 现象学 (hep-ph)

卫星晕的特性为暗物质（DM）物理提供了一个有希望的探测手段。 观测结果促使当前努力解释出人意料的致密DM晕。 如果DM不是无碰撞的，而是具有强烈的自相互作用，晕可以经历重力热坍缩，导致晕中心区域的密度更高。 然而，从第一性原理建模这一坍缩阶段是具有挑战性的。 为了改进这一点，我们试图更好地理解自相互作用暗物质（SIDM）在坍缩阶段的数值挑战和收敛性质。 特别是，我们旨在更好地理解卫星晕的演化。 为此，我们在孤立状态和外部引力势中运行了一个低质量晕的SIDM N体模拟。 模拟设置受到GD-1恒星流扰动者的启发。 我们发现，晕的演化对能量守恒误差非常敏感，而过大的SIDM核尺寸会人为地加速坍缩。 此外，我们证明了King模型可以描述我们模拟的后期阶段的小半径处的密度分布。 此外，对于我们的最高分辨率模拟（N = 5x10^7），我们公开了数据。 它可以作为基准。 总体而言，我们发现当前的数值方法在晚期坍缩阶段不会出现收敛问题，并提供了如何选择数值参数的指导，例如，能量守恒误差应保持在1%以下。 这使得能够运行晕的模拟，这些晕足够集中以解释GD-1类恒星流或强引力透镜系统的观测。 显示英文摘要

The properties of satellite halos provide a promising probe for dark matter (DM) physics. Observations motivate current efforts to explain surprisingly compact DM halos. If DM is not collisionless but has strong self-interactions, halos can undergo gravothermal collapse, leading to higher densities in the central region of the halo. However, it is challenging to model this collapse phase from first principles. To improve on this, we seek to better understand numerical challenges and convergence properties of self-interacting dark matter (SIDM) N-body simulations in the collapse phase. Especially we aim for a better understanding of the evolution of satellite halos. To do so, we run SIDM N-body simulations of a low mass halo in isolation and within an external gravitational potential. The simulation setup is motivated by the perturber of the stellar stream GD-1. We find that the halo evolution is very sensitive to energy conservation errors, and a too large SIDM kernel size can artificially speed up the collapse. Moreover, we demonstrate that the King model can describe the density profile at small radii for the late stages that we have simulated. Furthermore, for our highest-resolved simulation (N = 5x10^7) we make the data public. It can serve as a benchmark. Overall, we find that the current numerical methods do not suffer from convergence problems in the late collapse phase and provide guidance on how to choose numerical parameters, e.g. that the energy conservation error is better kept well below 1%. This allows to run simulations of halos becoming concentrated enough to explain observations of GD-1 like stellar streams or strong gravitational lensing systems.

[90] arXiv:2507.02757 (替换) [中文pdf, pdf, html, 其他]

标题： 发现和初步表征第三个星际物体：3I/ATLAS 显示英文标题

标题： Discovery and Preliminary Characterization of a Third Interstellar Object: 3I/ATLAS

Darryl Z. Seligman, Marco Micheli, Davide Farnocchia, Larry Denneau, John W. Noonan, Henry H. Hsieh, Toni Santana-Ros, John Tonry, Katie Auchettl, Luca Conversi, Maxime Devogèle, Laura Faggioli, Adina D. Feinstein, Marco Fenucci, Marin Ferrais, Tessa Frincke, Olivier R. Hainaut, Kyle Hart, Andrew Hoffman, Carrie E. Holt, Willem B. Hoogendam, Mark E. Huber, Emmanuel Jehin, Theodore Kareta, Jacqueline V. Keane, Michael S. P. Kelley, Tim Lister, Kathleen Mandt, Dušan Marčeta, Karen J. Meech, Mohamed Amine Miftah, Marvin Morgan, Francisco Ocaña, Eloy Peña-Asensio, Benjamin J. Shappee, Robert J. Siverd, Aster G. Taylor, Michael A. Tucker, Richard Wainscoat, Robert Weryk, James J. Wray, Atsuhiro Yaginuma, Bin Yang, Quanzhi Ye, Qicheng Zhang

评论： 提交至AAS期刊。13页，8图，1表。社区后续组织可在此处找到：https://3i-atlas.github.io/ 该论文的showyourwork!版本可在此处找到：https://github.com/3I-ATLAS/discovery-paper

主题： 地球与行星天体物理学 (astro-ph.EP) ; 星系的天体物理学 (astro-ph.GA) ; 天体物理学的仪器与方法 (astro-ph.IM)

我们报告初步观察结果，旨在表征第三个星际物体候选者。 该物体3I/ATLAS或C/2025 N1（ATLAS）于2025年7月1日世界时被发现，其轨道偏心率为$e\sim6.1$，近日点为$q\sim 1.36$天文单位，倾角为$\sim175^\circ$，以及双曲线速度为$V_\infty\sim 58$公里每秒$^{-1}$。 我们报告使用加拿大-法国-夏威夷望远镜和甚大望远镜获得的深度叠加图像，这些图像解析出了一个紧凑的彗发。 使用来自多个较小地面望远镜的图像，我们在$\sim4$天的时间跨度内发现该物体的光变曲线变化最小。 该物体的可见/近红外光谱斜率为17.1$\pm$0.2%/100纳米，与其他星际物体以及原始太阳系小天体（彗星和D型小行星）相当，尽管这一结果可能受到彗发污染的影响。 3I/ATLAS将在2025年9月初之前可观测，然后由于太阳张角较低，在近日点附近将无法被地球上的观测站观测到。 它将在2025年11月下旬再次从地面上可观测。 尽管这种限制不幸地禁止了在3I/ATLAS活动可能达到峰值的近日点进行详细的地球观测，但火星上的航天器可以在此时进行有价值的观测。 鼓励通过地面和空间望远镜，以及可能位于火星上的航天器对3I/ATLAS进行额外的测光、光谱和偏振监测，以表征3I/ATLAS的自转光变曲线、活动演化、非引力加速度以及形成条件的组成指标。 显示英文摘要

We report initial observations aimed at the characterization of a third interstellar object candidate. This object, 3I/ATLAS or C/2025 N1 (ATLAS), was discovered on 2025 July 1 UT and has an orbital eccentricity of $e\sim6.1$, perihelion of $q\sim 1.36$ au, inclination of $\sim175^\circ$, and hyperbolic velocity of $V_\infty\sim 58$ km s$^{-1}$. We report deep stacked images obtained using the Canada-France-Hawaii Telescope and the Very Large Telescope that resolve a compact coma. Using images obtained from several smaller ground-based telescopes, we find minimal light curve variation for the object over a $\sim4$ day time span. The visible/near-infrared spectral slope of the object is 17.1$\pm$0.2 %/100 nm, comparable to other interstellar objects and primitive solar system small bodies (comets and D-type asteroids), although this result is likely affected by some coma contamination. 3I/ATLAS will be observable through early September 2025, then unobservable by Earth-based observatories near perihelion due to low solar elongation. It will be observable again from the ground in late November 2025. Although this limitation unfortunately prohibits detailed Earth-based observations at perihelion when the activity of 3I/ATLAS is likely to peak, spacecraft at Mars could be used to make valuable observations at this time. Additional photometric, spectroscopic, and polarimetric monitoring of 3I/ATLAS by ground- and space-based telescopes, and possibly spacecraft based at Mars, are highly encouraged for characterizing 3I/ATLAS's rotational light curve, activity evolution, nongravitational acceleration, and compositional indicators of formation conditions.