The Heating and Ionization of Diffuse Interstellar Gas in the Disk and Halo of the Galaxy

Madsen博士被授予MPS杰出国际博士后研究奖学金，在英澳天文台进行海外研究项目。星际介质（ISM）是所有恒星形成的物质，并不断被垂死恒星的物质所丰富。它在理解银河系的所有组成部分如何协同工作方面起着至关重要的作用。在过去的几十年里，一个广泛分布的扩散电离氢层已经被确定为银河系ISM的主要组成部分之一。然而，关于这种气体的起源和物理条件的许多重要问题仍然存在。威斯康星h - α映射器（WHAM）设备是一个独特的法布里-珀罗光谱仪，专门研究这种气体的微弱发射。WHAM最近完成了一项北方天空调查，首次揭示了扩散电离气体的分布和运动学。这个项目将使用WHAM来探索调查开辟的新研究领域。它将解决与这种气体的加热和电离有关的几个问题，包括银河系内部的物理条件，广泛存在的中性气体和电离气体之间的一般关系，以及电离光子逃逸到银河系的光晕中。这项研究将在英澳天文台进行，与澳大利亚天文学家建立长期的科学合作将产生更广泛的影响。这将汇集具有相似科学和仪器专业知识的美国和澳大利亚科学家，其长期目标是实现未来探索南半球扩散电离气体的仪器。

Dr. Madsen is awarded an MPS Distinguished International Postdoctoral Research Fellowship to conduct a research program abroad at the Anglo-Australian Observatory. The interstellar medium (ISM) is the material out of which all stars are formed and is continuously enriched by material from dying stars. It plays a vitally important role in understanding how all the components of the Galaxy work together. In the past few decades, a widespread layer of diffuse, ionized hydrogen has been established as one of the principal components of the ISM in the Galaxy. However, many important questions regarding the origin and physical conditions of this gas still remain. The Wisconsin H-Alpha Mapper (WHAM) facility is a unique Fabry-Perot spectrometer dedicated to studying faint emission from this gas. WHAM has recently completed a Northern Sky Survey revealing the distribution and kinematics of diffuse ionized gas for the first time.This project will use WHAM to explore new areas of research opened up by the survey. It will address several issues pertaining to the heating and ionization of this gas, including the physical conditions in the inner parts of the Galaxy, the general relationship between the widespread neutral and ionized gas, and the escape of ionizing photons out into the halo of the Galaxy. This research will be carried out at the Anglo-Australian Observatory, with the broader impact of establishing a long-term scientific collaboration with Australian astronomers. This will bring together U.S. and Australian scientists with similar scientific and instrumental expertise, with the long-term goal of realizing a future instrument to explore diffuse ionized gas in the southern hemisphere.