发表机构
School of Earth & Space Exploration, Arizona State University; Department of Physics & Astronomy, Johns Hopkins University; Presbyterian College; Space Telescope Science Institute; Center for Astrophysical Sciences, William H. Miller III Department of Physics & Astronomy, Johns Hopkins University（亚利桑那州立大学地球与空间探索学院; 约翰斯·霍普金斯大学物理与天文学系; 长老会学院; 太空望远镜科学研究所; 约翰斯·霍普金斯大学威廉·H·米勒三世天体物理学科学中心物理与天文学系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究在距星暴星系139千秒差距处探测到分子氢，发现其由星系风与气体晕相互作用形成，具有高分子氢比例和单一冷温度，为理解星系周围分子氢分布提供新见解。
AI 中文摘要
分子氢（H$_2$）是星系中恒星形成的关键成分。然而，H$_2$在星系内部及周围的分布是天文学中的一个未解问题。我们报告了在距离一个星暴发光红外星系139千秒差距的独特环境中探测到H$_2$（覆盖激发能级$J = 0$至3）。这是迄今为止直接探测到H$_2$距离星系最远的一次。这个H$_2$系统与以往所见任何系统都不同，具有高的分子与原子氢比率（2%）和伴随的低中性氢柱密度（log$_{10}[N($H I$)/\text{cm}^{-2}] = 18.52^{+0.13}_{-3.58}$）。我们的测量揭示，含有H$_2$的云团相对于宿主星系以约100公里每秒的速度运动，具有超太阳金属丰度，并在单一冷温度（$245^{+25}_{-21}$ K）下激发，表明缺乏在其他H$_2$云中看到的“典型”核-包层结构。此外，我们的分析指出，H$_2$可能是通过星系风与星系周围气态晕之间的相互作用形成的。该云团的性质表明H$_2$是短寿命的，但它为风-日冕气体相互作用（CGM）的微观物理学提供了关键信息。
英文摘要
Molecular hydrogen (H$_2$) is the key ingredient for star formation in galaxies. However, how H$_2$ is distributed in and around galaxies is an open question in astronomy. We report the detection of H$_2$ (covering excitation levels $J = 0$ to 3) in a unique environment at a distance of 139 kpc from a starbursting luminous infrared galaxy. This is the furthest from a galaxy that H$_2$ has been directly detected to date. This H$_2$ system is unlike any seen before, with a high molecular-to-atomic hydrogen ratio (2%) and an accompanying low neutral hydrogen column density (log$_{10}[N($H I$)/\mathrm{cm}^{-2}] = 18.52^{+0.13}_{-3.58}$). Our measurements reveal that the H$_2$ bearing cloud is traveling at $\sim$100 km s$^{-1}$ relative to the host galaxy, has a super-solar metallicity, and excites at a single, cold temperature ($245^{+25}_{-21}$ K) indicating a lack of the ''typical'' core-envelope structure seen in other H$_2$ clouds. Furthermore, our analysis points to the H$_2$ likely being formed through interactions between galactic winds and the gaseous halo surrounding the galaxy. The properties of this cloud suggest that the H$_2$ is short-lived, yet it presents crucial information on the microphysics of the wind-CGM interactions.
Comments14 pages, 3 figures, 2 tables, Accepted for publication in ApJL
