Constraining Merging Galaxy Clusters with X-ray and Lensing Simulations and Observations: The case of Abell 2146

TL;DR

This study uses simulations and observations of the galaxy cluster Abell 2146 to understand how merger parameters influence X-ray and lensing signals, refining estimates of the merger's geometry and dynamics.

Contribution

It introduces a simulation-based approach to constrain merger configurations using X-ray and lensing data, specifically applied to Abell 2146, improving understanding of merger geometry.

Findings

Weak lensing mass estimates are overestimated due to gravitational compression.

The merger axis is tilted up to 30° from the plane of the sky.

Merger shock properties are sensitive to merger parameters.

Abstract

Galaxy cluster mergers are a powerful laboratory for testing cosmological and astrophysical models. However, interpreting individual merging clusters depends crucially on their merger configuration, defined by the masses, velocities, impact parameters, and orientation of the merger axis with respect to the plane of the sky. In this work, we investigate the impact of merger parameters on the X-ray emitting intracluster medium and gravitational lensing maps using a suite of idealised simulations of binary cluster mergers performed using the GAMER-2 code. As a test case, we focus on modeling the Bullet Cluster-like merging system Abell 2146, in which deep \textit{Chandra} X-ray and lensing observations revealed prominent merger shocks as well as the mass distribution and substructures associated with this merging cluster. We identify the most interesting parameter combinations, and evaluate the effects of various parameters on the properties of merger shocks observed by deep \textit{Chandra} and lensing observations. We show that due gravitational compression of the cluster halos during the merger, previous mass estimates from weak lensing are too high. The plane of the merger is tilted further from the plane of the sky than estimated previously, up to $30^\circ$ from the plane of the sky. We discuss the applicability of our results to multi-wavelength observations of merging galaxy clusters and their use as probes of cosmology and plasma physics.