A cold front in a preheated galaxy cluster

Abstract

We present a simulated cluster of galaxies, modeled with a preheated intracluster medium, that exhibits X-ray features similar to the cold fronts seen in Chandra observations. Mock observations at a particular epoch show factor of 2 discontinuities in X-ray temperature and factor of 4 discontnuities in surface brightness on a spatial scale less than or similar to100 kpc. Analysis of the cluster's dynamical history reveals that the front is a transient contact discontinuity created by an ongoing merger of two roughly equal mass subgroups. The cold front feature in this realization is amplified by the adiabatic expansion of one of the subgroups following its ablation from the center of its local dark matter potential. The presence of cold front features in a cluster modeled without radiative cooling or magnetic fields implies that such relatively complex physics is perhaps not a necessary element of the phenomenon and suggests that the prevalence of such features in high-resolution X-ray images of clusters may simply reflect the high frequency of ongoing mergers driven by gravity and comparatively simple hydrodynamics.