Testing the radio halo-cluster merger scenario. The case of RXCJ2003.5-2323

TL;DR

This study combines radio, X-ray, and optical data to investigate the giant radio halo in galaxy cluster RXCJ2003.5-2323, supporting the scenario that it results from a recent or ongoing cluster merger.

Contribution

It provides multiwavelength observational evidence linking the radio halo morphology to cluster merger activity, confirming the unrelaxed state of RXCJ2003.5-2323.

Findings

The cluster hosts a large, powerful radio halo.

The radio halo shows filamentary and clumpy morphology.

The cluster is dynamically unrelaxed, consistent with merger activity.

Abstract

We present a combined radio, X-ray and optical study of the galaxy cluster RXCJ2003.5-2323. The cluster hosts one of the largest, most powerful and distant giant radio halos known to date, suggesting that it may be undergoing a strong merger process. The aim of our multiwavelength study is to investigate the radio-halo cluster merger scenario. We studied the radio properties of the giant radio halo in RXCJ2003.5-2323 by means of new radio data obtained at 1.4 GHz with the Very Large Array, and at 240 MHz with the Giant Metrewave Radio Telescope, in combination with previously published GMRT data at 610 MHz. The dynamical state of the cluster was investigated by means of X-ray Chandra observations and optical ESO--NTT observations. Our study confirms that RXCJ2003.5-2323 is an unrelaxed cluster. The unusual filamentary and clumpy morphology of the radio halo could be due to a combination of the filamentary structure of the magnetic field and turbulence in the inital stage of a cluster merger.