Chandra Observations of the Spectacular A3411–12 Merger Event

Abstract

We present deep Chandra observations of A3411–12, a remarkable merging cluster that hosts the most compelling evidence for electron reacceleration at cluster shocks to date. Using the scaling relation, we find r 500  ∼ 1.3 Mpc, , , and a gas mass of . The gas mass fraction within r 500 is . We compute the shock strength using density jumps to conclude that the Mach number of the merging subcluster is small ( ). We also present density, temperature, pseudo-pressure, and pseudo-entropy maps. Based on the pseudo-entropy map, we conclude that the cluster is undergoing a mild merger, consistent with the small Mach number. On the other hand, radio relics extend over Mpc scale in the A3411–12 system, which strongly suggests that a population of energetic electrons already existed over extended regions of the cluster.