Simulations of Galaxy Cluster Collisions with a Dark Plasma Component
  Dark plasma is an intriguing form of self-interacting dark matter with an
effective fluid-like behavior, which is well motivated by various theoretical
particle physics models. We aim to find an explanation for an isolated mass
clump in the Abell 520 system, which cannot be explained by traditional models
of dark matter, but has been detected in weak lensing observations. We
performed N-body smoothed particle hydrodynamics simulations of galaxy cluster
collisions with a two component model of dark matter, which is assumed to
consist of a predominant non-interacting dark matter component and a 10-40
percent mass fraction of dark plasma. The mass of a possible dark clump was
calculated for each simulation in a parameter scan over the underlying model
parameters. In two higher resolution simulations shock-waves and Mach cones
were observed to form in the dark plasma halos. By choosing suitable simulation
parameters, the observed distributions of dark matter in both the Bullet
Cluster (1E 0657-558) and Abell 520 (MS 0451.5+0250) can be qualitatively
reproduced.
