An XMM-Newton view of the merging activity in the Centaurus cluster

TL;DR

This study uses XMM-Newton data to analyze merging activity in the Centaurus cluster, confirming shock heating and metallicity retention around Cen 45, revealing complex thermodynamic and chemical structures indicative of ongoing merger processes.

Contribution

It provides new X-ray observational evidence of shock heating, metallicity distribution, and entropy variations during a cluster merger, enhancing understanding of cluster dynamics.

Findings

Temperature excess around Cen 45 explained by shock heating.

Significant metallicity excess indicating gas retention.

Pressure and entropy variations consistent with merger activity.

Abstract

We report the results of XMM-Newton observations of the regions around the core of the Centaurus cluster where evidence for merging activity between the subgroup Cen 45 and the main Centaurus cluster has previously been observed using ASCA and ROSAT data. We confirm the ASCA findings of a temperature excess surrounding Cen 45. We find that this temperature excess can be explained using simple shock heating given the large line of sight velocity difference between Cen 45 and the surrounding main Centaurus cluster. We find that there is a statistically significant excess in metallicity around Cen 45, showing that Cen 45 has managed to retain its gas as it has interacted with the main Centaurus cluster. There is a pressure excess to the east in the direction of the merger, and there is also an entropy excess around the central galaxy of Cen 45. The metallicity between 50-100 kpc to the north of NGC 4696 is higher than to the south, which may be the result of the asymmetric distribution of metals due to previous sloshing of the core, or which may be associated with the filamentary structure we detect between NGC 4696 and NGC 4696B.