Chandra Observations of the AS0295 Cluster

Abstract

Abstract We present deep (205 ks) Chandra observations of the AS0295 binary merging cluster (z = 0.30). In the X-ray image, the secondary component is clearly visible as a surface brightness peak, while the primary cluster has a flatter distribution. We found cool gas (∼6 keV) associated with the secondary, while the central temperature of the primary does not deviate significantly from the mean temperature of the cluster of ∼9.5 keV. In the vicinity of the primary’s core we found the hottest region in the cluster accompanied by a surface brightness discontinuity. We propose that this region corresponds to a shock, for which we estimate a Mach number of . We found other merger signatures such as a plume of cool gas emerging from the primary cluster and a cold front and a possible bow shock (Mach number of ) leading the secondary cluster. Based on the observed properties in comparison to binary merger simulations from the literature we propose for AS0295 a low-mass ratio, off-axis merging scenario, with the secondary close to the first apocenter. Comparison of our results with strong-lensing observations of AS0295 from Cibirka et al. shows an offset between the total mass peak and the bulk of the gas distribution in the primary cluster. The properties of the merger and the existence of the offset between mass peak and gas make AS0295 a promising candidate for the study of mergers involving non-cool core clusters and the nature of dark matter.