Dissertation Award for Mike Anderson

End of April 2014, the Rackham Graduate School at the University of Michigan awarded Mike Anderson with a ProQuest Distinguished Dissertation Award for his PhD thesis. These awards recognize "exceptional and unusually interesting" dissertations and are selected by the Michigan Society of Fellows.

Abb. 1: University of Michigan copyright: Andrew Horne

Abb. 2: Mike Anderson during the award ceremony copyright: Whitney Miller

Mike Anderson's dissertation is entitled "Hot Gaseous Halos Around Galaxies". Questions about the existence and properties of such gaseous halos have been outstanding problems in the field of galaxy formation for decades. The official announcement of the award describes Anderson's research as follows:

Dr. Anderson's innovative and articulate thesis describes his rigorous and ultimately successful search for hot halo gas surrounding spiral galaxies. Theories of galaxy formation have long predicted the existence of this gas in systems such as our own; Dr. Anderson was the first to meaningfully detect it in two spiral galaxies and place strong limits on the overall quantity in the Milky Way. To do so, Dr. Anderson developed several new tools and approaches to the problem, spanning from leveraging the dispersion in pulsar timing in the Magellanic Clouds as probe of the intervening gas to an in-depth Bayesian analysis of stacked ROSAT all sky images. Additionally he introduced significant improvement in the spatial analysis of extended X-ray emission. In his thoughtful analysis, he reaches an extremely important conclusion the gas he detects is not sufficient to account for the "missing baryons" relative to the cosmological baryon fraction. He argues that galactic winds do not expel the gas at low redshift, and he suggests early ejection via pre-heating of the intergalactic medium, ejective feedback via star-formation/AGN, or circumgalactic medium recycling are a likely means for the redistribution of the missing gas. These conclusions prime the field for many more interesting investigations. His eloquent framing of his initial motivation, scientific process and ultimate conclusions make for a strong and compelling thesis.

This work has earned Anderson one of the ten ProQuest Distinguished Dissertation Awards from the University of Michigan for 2013, chosen from more than 800 dissertations, which the university granted that year. The University of Michigan’s graduate programs are consistently ranked as some of the best in the United States. This is the seventh year of the award’s history at Michigan. The ProQuest Distinguished Dissertation Award also comes with a $1000 honorarium, as well as reimbursement for travel and lodging. The official award ceremony took place on 29 April 2014 in Rackham Auditorium on the campus of the University in Ann Arbor, Michigan.

At MPA, Anderson is continuing to research the missing mass from galaxies from a number of directions. He is involved in several new observations of hot gaseous halos, both targeted observations and stacking analyses. He is also working on observations and theoretical analysis of the interplay between supermassive black holes at the centres of massive galaxies and the hot gaseous halos around the galaxies. Finally, he intends to examine the baryon budget of galaxies in the early Universe as well.