A cluster pair : A3532 and A3530

TL;DR

This study investigates the galaxy clusters A3532 and A3530, revealing signs of galaxy-scale mergers, possible tidal interactions, and complex substructures, while finding no evidence of large-scale cluster mergers or core disruptions.

Contribution

It provides a detailed multi-wavelength analysis of the cluster pair, highlighting signs of galaxy-scale mergers and interactions, and discusses the nature of the overlapping X-ray emission region.

Findings

Presence of substructures in A3532's core.

Signs of galaxy-scale mergers in A3532.

Overlapping X-ray emission likely due to tidal interactions.

Abstract

We present a detailed study of a close pair of clusters of galaxies, A3532 and A3530, and their environments. The \textit{Chandra} X-ray image of A3532 reveals presence of substructures on scales of $\sim$20$^{\prime\prime}$ in its core. XMM-Newton maps of the clusters show excess X-ray emission from an overlapping region between them. Spectrally determined projected temperature and entropy maps do not show any signs of cluster scale mergers either in the overlapping region or in any of the clusters. In A3532, however, some signs of the presence of galaxy scale mergers are visible e.g., anisotropic temperature variations in the projected thermodynamic maps, a wide angled tailed (WAT) radio source in the brighter nucleus of its dumbbell Brightest Cluster Galaxy (BCG), and a candidate X-ray cavity coincident with the northwestern extension of the WAT source in the low-frequency radio observations. The northwestern extension in A3532 seems either a part of the WAT or an unrelated diffuse source in A3532 or in the background. There is an indication that the cool core in A3532 has been disrupted by the central AGN activity. A reanalysis of the redshift data reinforces the close proximity of the clusters. The excess emission in the overlapping region appears to be a result of tidal interactions as the two clusters approach each other for the first time. However, we can not rule out the possibility of the excess being due to the chance superposition of their X-ray halos.