Nov 11 (Wed), 14:15 in A315
While dark matter self-interactions may solve several problems with structure formation, so far only the effects of two-body scattering of dark matter particles have been considered. I will discuss a scenario where a subdominant component of dark matter is charged under an unbroken U(1) gauge group. In this case collective plasma effects need to be taken into account to understand the dynamics of the interacting DM. Plasma instabilities can lead to collisionless dark matter shocks in galaxy cluster mergers. I will discuss the observations made in the Abell 3827 and 520 clusters in this context.