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.
