Witnessing a merging bullet being stripped in the galaxy cluster RXCJ2359.3-6042

Abstract

We report the discovery of the merging cluster, RXCJ2359.3-6042, from the REFLEX II cluster survey and present our results from all three detectors combined in the imaging and spectral analysis of the XMM-Newton data. Also known as Abell 4067, this is a unique system, where a compact bullet penetrates an extended, low density cluster at redshift z = 0.0992 clearly seen from our follow-up XMM-Newton observation. The bullet goes right through the central region of the cluster without being disrupted and we can clearly see how the bullet component is stripped of its layers outside the core. There is an indication of a shock heated region in the east of the cluster with a higher temperature. The bulk temperature of the cluster is about 3.12(±0.13) keV implying a lower mass system. Spearheading the bullet is a cool core centred by a massive early type galaxy. The temperatures and metallicities of a few regions in the cluster derived from the spectral analysis supports our conjecture based on the surface brightness image that a much colder compact component at 1.55(±0.10) keV with large metallicity (0.75 Z⊙) penetrates the main cluster, where the core of the infalling component survived the merger and left stripped gas behind at the centre of the main cluster. We also give an estimate of the total mass within r500, which is about 2 × 1014 M⊙ from the deprojected spherical β modelling of the cluster in good agreement with other mass estimates from the M − TX and M − σv relations.