Particle Physics Seminar: Self-Interacting Dark Matter and the Orbital Evolution of Satellite Galaxies

Abstract:

We demonstrate that self interactions between dark matter particles can leave distinctive signatures on the distribution of satellite galaxies around Milky Way-like galaxies. In particular, self-interacting dark matter (SIDM) affects satellite mass loss through tidal stripping, ram-pressure evaporation, and gravothermal collapse. We delineate the regions of SIDM parameter space, specified by interaction cross section and velocity scale, where each of these effects dominates, and show how the relative mass loss depends on the satellite's initial mass, density profile and orbit. When the rate of ram-pressure evaporation far exceeds the tidal stripping rate, the satellite's inner density rapidly drops after any pericentric passage. This allows us to place a new constraint on SIDM based on the observed properties of the Draco dwarf galaxy, which is one of the densest known dwarfs in the Milky Way. Our results suggest that observational studies of dwarf galaxies around galaxies like the Milky Way can play an integral role in testing the SIDM hypothesis.

Seminar Organizers: Prof. Erez Etzion & Dr. Liron Barak