X-ray study of Abell 3365 with XMM-Newton

Abstract

We present an X-ray spectral analysis using XMM-Newton/EPIC observations (∼100 ks) of the merging galaxy cluster Abell 3365 (z = 0.093). Previous radio observations suggested the presence of a peripheral elongated radio relic to the east and a smaller radio relic candidate to the west of the cluster center. We find evidence of temperature discontinuities at the location of both radio relics, indicating the presence of a shock with a Mach number of ℳ = 3.5 ± 0.6 towards the east and a second shock with ℳ = 3.9 ± 0.8 towards the west. We also identify a cold front at r ∼ 1.6′ from the X-ray emission peak. Based on the shock velocities, we estimate that the dynamical age of the main merger along the east-west direction is ∼0.6 Gyr. We find that the diffusive shock acceleration scenario from the thermal pool is consistent with the electron acceleration mechanism for both radio relics. In addition, we studied the distribution of the temperature, iron (Fe) abundance, and pseudo-entropy along the merging axis. Our results show that remnants of a metal-rich cool-core can partially or entirely survive after the merging activity. Finally, we find that the merger can displace the metal-rich and low entropy gas from the potential well towards the cold front, as has been suggested via numerical simulations.