标题： 隐藏在尘埃幕后的星系：银河系盘面后一个超亮强透镜化红移 z = 3.75 星系的气体和尘埃特性 显示英文标题

标题： Hiding behind a curtain of dust: Gas and dust properties of an ultra-luminous strongly-lensed z = 3.75 galaxy behind the Milky Way disk

摘要： 我们对位于卢西斯-I分子云后的强透镜亚毫米波星系J154506进行了详细分析，并对其物理特性进行了表征。 利用档案数据和新数据（包括亚角秒分辨率（$\sim0.75$）的ALMA观测数据、VLT/MUSE和FORS2光学数据，以及ACA和LMT的光谱扫描）我们识别出两个高显著性（SNR>5）的发射线，频率分别为97.0和145.5 GHz，分别对应CO(4-3)和CO(6-5)。 这些检测得出光谱红移为$z_{\rm{spec}}=3.7515\pm 0.0005$。 我们还使用阿塔卡马路径探测实验（APEX）检测到[CII] 158$\mu$m精细结构线在400 GHz处，进一步确认了红移并提供了关于J154506物理特性的见解。 通过在uv平面上建模ALMA Band 6和7的连续谱数据，我们得出平均放大因子为$6.0 \pm 0.4$，我们的分析显示该星暴星系中尘埃相对较冷（$\sim$37 K），具有高固有尘埃质量（$\sim2.5\times10^{9}~\rm{M}_{\odot}$）和红外（IR）光度（$\sim6\times10^{12}~\rm{L}_{\odot}$）。 尘埃SED最好由中等密度分子气体（$10^2-10^4\rm{cm}^{-3}$）主导的模型来再现，这表明远红外辐射主要来自弥散区域，而不是极端星爆或AGN典型的致密、高压环境。 这一结论得到了尘埃温度与动能温度接近于1的比值的支持，这反驳了高度能量加热机制的存在。 CO激发阶梯在CO(5-4)附近达到峰值，并由稍为致密的分子气体主导。 我们的结果强调了远红外和亚毫米观测的独特能力，即使被前景分子云遮挡，也能揭示和表征稀少的强透镜高红移星系。 显示英文摘要

摘要： We present a detailed analysis of J154506, a strongly lensed submillimeter galaxy (SMG) behind the Lupus-I molecular cloud, and characterization of its physical properties. Using a combination of archival and new data (including sub-arcsecond resolution ($\sim0.75$) ALMA observations, VLT/MUSE and FORS2 optical data, as well as spectral scans from the ACA and the LMT) we identify two high-significance (SNR>5) emission lines at 97.0 and 145.5 GHz, corresponding to CO(4-3) and CO(6-5), respectively. These detections yield a spectroscopic redshift of $z_{\rm{spec}}=3.7515\pm 0.0005$. We also report the detection of the [CII] 158 $\mu$m fine-structure line at 400 GHz using the Atacama Pathfinder Experiment (APEX), further confirming the redshift and providing insights into J154506's physical properties. By modeling ALMA Band 6 and 7 continuum data in the uv-plane, we derive an average magnification factor of $6.0 \pm 0.4$ and our analysis reveals a relatively cold dust ($\sim$37 K) in a starburst galaxy with a high intrinsic dust mass ($\sim2.5\times10^{9}~\rm{M}_{\odot}$) and infrared (IR) luminosity ($\sim6\times10^{12}~\rm{L}_{\odot}$). The dust SED is best reproduced by a model dominated by moderately dense molecular gas ($10^2-10^4\rm{cm}^{-3}$), indicating that the far-infrared emission arises primarily from diffuse regions rather than compact, high-pressure environments typical of extreme starbursts or AGN. This is supported by the close-to-unity ratio between the dust and kinetic temperatures, which argues against highly energetic heating mechanisms. The CO excitation ladder peaks close to CO(5-4) and is dominated by slightly denser molecular gas. Our results underscore the unique power of far-IR and submillimeter observations to both uncover and characterize scarce, strongly lensed, high-redshift galaxies, even when obscured by foreground molecular clouds.