Colloquium: Dr. Liliya WilliamsMinnesota Institute for Astrophysics University of Minnesota Minneapolis, MN
Dark Matter Halos from First Principles
Multiples lines of evidence indicate that all galaxies and clusters of galaxies live in dark matter (DM) halos. The properties of the halos are consistent with the DM particles being cold, i.e. non-relativistic, and interacting only through gravity. Assuming these basic particle properties, and using N-body simulations, one can arrive at the detailed properties of DM halos, such as their density and velocity dispersion profiles. However, the physical origin of these halo properties --- why do simulations produce these density profiles instead of some other ones? --- are still not understood. In this talk I will describe a first principles statistical mechanical approach that derives steady state properties of isotropic collisionless self-gravitating systems. This prediction is a very good match to the results of N-body simulations. I will discuss the implications of this prediction, and some current and future work.