The Nature of the Dark, Diffuse Interstellar Medium in the Local Group

Michael Busch被授予美国国家科学基金会天文学和天体物理学奖学金，在加州大学圣地亚哥分校开展研究和教育项目。Busch将对羟基自由基（OH）进行射电天文观测，以研究附近星系星际介质（ISM）的性质和分子氢（H2）含量。这些观测将补充对一氧化碳（CO）的观测——一种广泛使用的H2探针——以揭示无法用CO研究的“暗H2”气体，以及那些原子氢（HI）。这项研究的结果将使天文学家了解原子气体如何转变为分子气体。对于该项目的教育部分，Busch将开发一个使用便携式天文馆的研讨会，以增加小学生对天文学的参与。该研究项目将生成大型的氢氧根地图，从而可靠地推断两个代表性的本星系群中弥漫暗氢的分布。结合CO和HI观测，这将使ISM的环境，质量和运动学的全面表征成为可能。观测和分析将有助于以前所未有的细节阐明暗H2的性质，对ISM中原子和分子气体之间的转变产生独特的见解。这个项目的数据对天体化学、恒星形成和星系结构的研究也很有用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Michael Busch is awarded an NSF Astronomy and Astrophysics Fellowship to carry out a program of research and education at the University of California, San Diego. Busch will perform radio astronomical observations of the hydroxyl radical (OH) to study the properties and molecular hydrogen (H2) content of the interstellar medium (ISM) of nearby galaxies. The observations will complement observations of carbon monoxide (CO) – a widely used probe of H2 – to shed light on “dark H2” gas that cannot be studied using CO, as well as those of atomic hydrogen (HI). Results from the study will allow astronomers to understand how atomic gas undergoes the transition to molecular gas. For the education component of this project, Busch will develop a workshop on using a portable planetarium to increase astronomy engagement with grade school students.This research project will generate large maps of OH allowing reliable inference of the distribution of diffuse dark H2 in two representative local group galaxies. Combined with CO and HI observations, this will enable a thorough characterization of the environment, mass, and kinematics of the ISM. The observations and analyses will help elucidate the nature of dark H2 in unprecedented detail, yielding unique insight into the transition between the atomic and molecular gas in the ISM. Data from this project will also be useful for studies of astrochemistry, star formation, and galactic structure.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.