Self-interacting dark matter on small and large scales

In the self-interacting dark matter paradigm (hereafter SIDM), dark matter (DM) is assumed to have non-gravitational interactions with itself. SIDM has been constrained by observations of galaxy clusters. More recently, measurements of large DM densities at the center of the Milky Way’s galaxy satellites are indicating that DM-DM interactions can potentially induce gravothermal core collapse. In this proceeding an overview of the combined measurements of cluster-size galaxies and kinematics of local satellite galaxies is used to argue that DM interactions should depend on the relative velocity of the DM particles.