Galactic Dark Matter Halo and Stellar Bar Coupling


Fri, 12 Mar 2021, 03:00 pm - 04:00 pm
Spring 2021
Dr. Angela Collier
University of Colorado


A majority of disk galaxies host stellar bars that are the prime driver of internal galaxy evolution. Bars also trigger the flow of angular momentum between the disks and their parent dark matter (DM) halos. Using high-resolution N-body stellar and DM numerical simulations, I model and analyze the dynamical and secular evolution of stellar bars in disk galaxies and their DM counterparts, including the induced DM bars in spinning halos with a range of cosmological spin parameter. My main results emphasize a new effect: the DM halo spin has a profound effect on the evolution of stellar and DM bars. Broadly, I find that secular torques between stellar bars and DM halo orbits lead to a coupling that lasts for the lifetime of the bar. Most importantly, the stellar bars dissolve when residing in halos of large prograde spin. These disks can represent the unbarred branch of galaxies on the Hubble Fork Diagram. The dark matter over-densities produced by the halo-bar coupling provide a novel space where baryons are evacuated in which to look for DM annihilation or decay signals. I will describe the mechanisms that allows low inclination dark matter halo orbits to couple to the stellar bar and make predictions on the mass and location of previously unreported dark matter over-densities in our own Milky Way.