标题： Lyman α 参考样本。 XVI。 Lyman-$α$发射星系的全局 21 厘米 HI 性质 显示英文标题

标题： The Lyman Alpha Reference Sample. XVI. Global 21cm HI properties of Lyman-$α$ emitting galaxies

摘要： 氢的莱曼-$\alpha$（Lya）线是高红移星系的一个著名示踪剂。然而，Lya可观测量与星系属性之间的联系尚未完全建立，限制了该谱线用于探测星系物理的能力。在此，我们推导出附近Lya发射星系的总体中性氢（HI）气体属性，以评估HI对星系Lya输出的影响。我们使用VLA在D阵列配置下（约55弧秒分辨率，约38千秒差距）观测了来自Lyman Alpha参考样本（LARS和eLARS）的37个具有可用Lya图像的恒星形成星系的21厘米线发射。我们检测到33/37个被观测星系的21厘米发射。我们发现总体HI属性与通过HST测光推导出的Lya亮度、逃逸分数或等效宽度之间没有显著相关性。此外，Lya发射星系和弱发射或非发射星系在光学选择的z=0星系的HI参数空间中分布均匀。大约74%的样本正在经历星系相互作用，对于EW$\geq$20Å的星系而言，发射星系的比例更高（83%），而非发射或弱发射星系的比例较低（70%）。然而，被识别为相互作用的星系在Lya和HI属性上与非相互作用星系在统计上是一致的。我们的结果表明，总体HI属性（在大于30千秒差距的尺度上）对星系的Lya输出影响很小。相反，HI可能在小尺度上调节Lya发射：需要统计比较Lya和高角分辨率21厘米观测来全面评估HI在Lya辐射转移中的作用。尽管我们的研究表明星系合并可能在本地宇宙中Lya光子发射中起作用，特别是在HI比例较高的星系中，但最终决定Lya可观测量的是系统被观测的视线方向。 显示英文摘要

摘要： The Lyman-$\alpha$ (Lya) line of hydrogen is a well-known tracer of galaxies at high-z. However, the connection between Lya observables and galaxy properties has not fully been established, limiting the use of the line to probe the physics of galaxies. Here, we derive global neutral hydrogen gas (HI) properties of nearby Lya-emitting galaxies to assess the impact of HI on the Lya output of galaxies. We observed 21cm line emission using the VLA in D-array configuration (~55" resolution, ~38 kpc) for 37 star-forming galaxies with available Lya imaging from the Lyman Alpha Reference Samples (LARS and eLARS). We detect 21cm emission for 33/37 galaxies observed. We find no significant correlation of global HI properties with Lya luminosity, escape fraction or equivalent width derived with HST photometry. Additionally, both Lya-emitters and weak or non-emitters are distributed evenly along the HI parameter space of optically-selected z=0 galaxies. Around 74% of the sample is undergoing galaxy interaction, this fraction is higher for Lya-emitters (83% for galaxies with EW$\geq$20\r{A}) than for non or weak emitters (70%). Nevertheless, galaxies identified as interacting have Lya and HI properties statistically consistent with those of non-interacting galaxies. Our results show that global HI properties (on scales > 30kpc) have little direct impact on the Lya output from galaxies. Instead, HI likely regulates Lya emission on small scales: statistical comparisons of Lya and high angular resolution 21cm observations are required to fully assess the role of HI in Lya radiative transfer. While our study indicates that galaxy mergers could play a role in the emission of Lya photons in the local universe, especially for galaxies with high HI fractions, the line-of-sight through which a system is observed ultimately determines Lya observables.