Investigations of the Inner Dark Matter Density Profiles of Dwarf Galaxies


TAMU astronomy seminar.

Abstract: The Λ cold dark matter (DM) model successfully explains the distribution of large scale structure and the cosmic microwave background but, there are several problems concerning the distribution of DM on sub-galactic scales. In dispersion supported galaxies multiple stellar populations can be utilized as independent tracers to break modeling degeneracies and infer the mass slope. I present an analysis searching for multiple stellar populations in a new Keck/DEIMOS spectroscopic data set of the Milky Way satellite galaxy, Ursa Minor. I identify two chemodynamical stellar populations at high significance with distinct kinematic, metallicity, and spatial distributions. By utilizing their dynamics I measure the mass slope and find it is more consistent with a ‘cored’ halo than a ‘cuspy’ halo but systematics prevent a robust measurement. The self-interacting dark matter (SIDM) model provides a mechanism that modifies the DM distribution on sub-galactic scales. The thermalization due to self-interactions creates large cores and reduces dark matter densities. I show fits with SIDM models can explain both the inner and outer regions of galactic rotation curves. I will comment on an ongoing analysis searching for velocity gradients (a sign of tidal disruption) in Milky Way satellites in a uniform manner with quantified significance.