An approximate theory for substructure propagation in clusters

TL;DR

This paper introduces an analytical hydrodynamic model to predict the separation between dark matter and X-ray gas in merging galaxy clusters, aiding in understanding dark matter distribution and cluster dynamics.

Contribution

It presents a novel approximate analytical solution for substructure propagation in merging clusters and a new method to predict dark matter halo positions from X-ray data.

Findings

Successfully applied to clusters 1E0657-558 and Abell 1763

Provides estimates of the distance between X-ray and dark matter components

Determines the Mach number of merger shocks

Abstract

The existence of dark matter can be proved in an astrophysical context by the discovery of a system in which the observed baryons and the inferred dark matter are spatially segregated, such as the bullet cluster (1E0657-558). The full descriptions of the dark matter halo and X-ray gas substructure motions are necessary to forecast the location of the dark halo from X-ray maps, which can be confirmed by the detection of a galaxy concentration or by gravitational lensing. We present an analytical hydrodynamic model to determine the distance between the X-ray and dark-matter components and the Mach number of the merger shock. An approximate solution is given for the problem of the substructure propagation in merging clusters. A new method to predict the position of a dark matter halo in clusters, where there is a separation between the X-ray gas and the dark halo, is proposed and applied to the clusters 1E0657-558 and Abell 1763.