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The Washington Research Foundation Fellowship

Ryan Maas, Physics and Astronomy - 2007-08 RFAU

Ryan began doing research soon after taking an introductory astronomy class from his future advisor, Professor Julianne Dalcanton. After completing a summer project involving N-body simulations, he became involved in several others in that field at the University of Washington. His interests include such topics as the formation and evolution of galaxies, as well as investigating the nature of dark matter and dark energy.

Through his two major research projects, Ryan hopes to publish results that can be applied to future studies of astronomical objects and to contribute to a more complete understanding of the universe.

Mentors: Julianne Dalcanton, Astronomy Department, University of Washington; Victor P. Debattista, Astronomy Department, University of Central Lancashire

Project Title: Exploring Dark Matter Collisions in Dwarf Galaxies

Abstract: Dwarf spheroidal galaxies are much smaller than the Milky Way and have surface brightness profiles that fall off exponentially as opposed to the power law dependence of disk galaxies. It is not well known how these galaxies can be heated as much as they are without having collided into a larger galaxy. One possibility may be related to another cosmological theory known as hierarchal merging. From simulations it is believed that the largest galaxies in the universe were formed from the collision of much smaller clumps of matter, and that the number distribution of objects in the universe tends heavily to the halos that are less massive than the dwarf spheroidals themselves. While we do not see the number of dwarf galaxies predicted by hierarchal merging, the presence of these small dark matter halos may have a substantial impact on the morphology of objects like dwarf spheroidals. I am testing this hypothesis by creating initial conditions for impact simulations of this sort and comparing the results with observed data on dwarf galaxies to determine an upper limit on the heating produced. As the dark matter halos colliding with the galaxy cannot be observed there are many parameters which need to be tested, such as the mass, incidence, and energy of the colliding objects. The results of this project would reveal whether hierarchal merging is indeed responsible for the state of these dwarf galaxies or if another explanation must be found.