Diffuse radio emission in the complex merging galaxy cluster Abell 2069

TL;DR

This study detects and characterizes diffuse radio emissions, including a potential double-halo, in the merging galaxy cluster Abell 2069, providing insights into particle acceleration and magnetic fields during cluster mergers.

Contribution

First detection of a double-halo radio structure in a single galaxy cluster, combining WSRT and GMRT observations to analyze diffuse radio features in Abell 2069.

Findings

Identified a radio halo with flux density 25 +/- 9 mJy.

Detected a second diffuse source, possibly a mini-halo, with flux density 15 +/- 2 mJy.

First example of a double-halo in a merging galaxy cluster.

Abstract

Galaxy clusters with signs for a recent merger show in many cases extended diffuse radio features. This emission originates from relativistic electrons which suffer synchrotron losses due to the intra-cluster magnetic field. The mechanisms of the particle acceleration and the properties of the magnetic field are still poorly understood. We search for diffuse radio emission in galaxy clusters. Here, we study the complex galaxy cluster Abell 2069, for which X-ray observations indicate a recent merger. We investigate the cluster's radio continuum emission by deep Westerbork Synthesis Radio Telescope (WSRT) observations at 346 MHz and a Giant Metrewave Radio Telescope (GMRT) observation at 322 MHz. We find an extended diffuse radio feature roughly coinciding with the main component of the cluster. We classify this emission as a radio halo and estimate its lower limit flux density to 25 +/- 9 mJy. Moreover, we find a second extended diffuse source located at the cluster's companion and estimate its flux density to 15 +/- 2 mJy. We speculate that this is a small halo or a mini-halo. If true, this cluster is the first example of a double-halo in a single galaxy cluster.