Simulations of Galaxy Cluster Collisions with a Dark Plasma Component

TL;DR

This study uses simulations to explore how a dark plasma component in dark matter could explain observed mass distributions in galaxy cluster collisions, particularly in the Bullet Cluster and Abell 520.

Contribution

It introduces a two-component dark matter model including dark plasma and demonstrates its potential to reproduce observed phenomena in galaxy cluster collisions.

Findings

Dark plasma forms shock waves and Mach cones in simulations.

Simulations can qualitatively match observed dark matter distributions.

Dark plasma component explains the isolated mass clump in Abell 520.

Abstract

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.