Simulating the arrival of the southern substructure in the galaxy cluster Abell 1758

TL;DR

This study uses N-body hydrodynamical simulations to explore how the southern substructure in galaxy cluster Abell 1758 arrived, aiming to reproduce observed X-ray bridges and determine the most plausible orbital scenario.

Contribution

It introduces new simulations incorporating the southern substructure, testing various orbital configurations to match observed features in Abell 1758.

Findings

Tangential approach best matches X-ray surface brightness profiles.

Simulations show a detectable gas bridge in all tested scenarios.

X-ray excess amplitude overestimates observations by a factor of 2-3.

Abstract

Abell 1758 (z~0.278) is a galaxy cluster composed of two structures: A1758N and A1758S, separated by ~2.2 Mpc. The northern cluster is itself a dissociative merging cluster that has already been modelled by dedicated simulations. Recent radio observations revealed the existence of a previously undetected bridge connecting A1758N and A1758S. New simulations are now needed to take into account the presence of A1758S. We wish to evaluate which orbital configuration would be compatible with a bridge between the clusters. Using N-body hydrodynamical simulations that build upon the previous model, we explore different scenarios that could have led to the current observed configuration. Five types of orbital approaches were tested: radial, tangential, vertical, post-apocentric, and outgoing. We found that the incoming simulated scenarios are generally consistent with mild enhancements of gas density between the approaching clusters. The mock X-ray images exhibit a detectable bridge in all cases. Compared to measurements of Chandra data, the amplitude of the X-ray excess is overestimated by a factor of ~2--3 in the best simulations. The scenario of tangential approach proved to be the one that best matches the properties of the profiles of X-ray surface brightness. The scenarios of radial approach of vertical approach are also marginally compatible.