Effects of dark matter self-interaction on the evolution of the Sagittarius stream

Abstract

I present a novel test of self-interacting dark matter (SIDM) models by analyzing the impact of self-interaction on the infall of the Sagittarius (Sgr) dwarf spheroidal galaxy. A review of the history of dark matter evidence and the development of the ΛCDM cosmological model is included, followed by a review of the motivations for and viability of SIDM models. Sgr is then presented as a testbed for these models, since its unique orbital history is highly sensitive to the microphysics determining the Galactic gravitational potential. I present three simulations of the Sgr infall: two using collisionless dark matter with cuspy and cored initial galactic profiles, and one using self-interacting dark matter. It is found that the inclusion of dark matter self-interaction has profound impacts on the resulting shape and distribution of the Sgr stream. In particular, we find that the distribution of radial velocities is impacted substantially, with the SIDM merger unable to reconcile both the shape of the stream and the observed radial velocity of the progenitor.