Resilience of Sloshing Cold Fronts against Subsequent Minor Mergers

TL;DR

This study uses hydrodynamic and N-body simulations to show that sloshing cold fronts in galaxy clusters are generally resilient to subsequent minor mergers, especially off-axis ones, remaining observable for extended periods.

Contribution

It provides the first systematic analysis of how subsequent minor mergers affect the longevity of sloshing cold fronts in galaxy clusters.

Findings

SCFs are present in most configurations except shortly after the first core passage.

Head-on minor mergers significantly reduce SCFs, while off-axis mergers only moderately affect them.

Outer SCFs (>~500 kpc) are particularly resilient to subsequent mergers.

Abstract

Minor mergers are common in galaxy clusters. They have the potential to create sloshing cold fronts (SCFs) in the intracluster medium (ICM) of the cluster. However, the resilience of SCFs to subsequent minor mergers is unknown. Here we investigate the extent to which SCFs established by an off-axis minor merger are disrupted by a subsequent minor merger. We perform a suite of 13 hydrodynamic + N-body simulations of idealised triple cluster mergers in which we vary the approach direction and impact parameter of the tertiary cluster. Except for ~1 Gyr after the first core passage of the tertiary cluster, clear SCFs are present in all merger configurations. Subsequent head-on minor mergers reduce the number of SCFs significantly, while subsequent off-axis minor mergers only moderately reduce the number of SCFs. In particular, outer (>~500 kpc) SCFs are resilient. The results of this work indicate that SCFs are easily formed in the course of a minor merger and are long-lived even if a further minor merger takes place. SCFs thus should be ubiquitous, but deriving the merger history of a given cluster based on its observed SCFs might be more complex than previously thought.