Kavli Affiliate: Hsiaowen Chen
|Summary: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$)/mathrmcm^-2] = 18.52^+0.13_-3.58$). 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.| Search Query: arXiv Query: search_query=au:”Chen Hsiao-wen”&id_list=&start=0&max_results=10Read More