Early Science with the Karoo Array Telescope: a Mini-Halo Candidate in Galaxy Cluster Abell 3667

TL;DR

This study presents polarization observations of galaxy cluster Abell 3667, revealing a candidate mini-halo with properties consistent with known mini-halos, using the Karoo Array Telescope at GHz frequencies.

Contribution

First detection of a mini-halo candidate in Abell 3667 using full-polarization radio observations at 1.33 and 1.82 GHz.

Findings

Identification of a mini-halo candidate with flux density 67.2 mJy at 1.37 GHz.

The mini-halo's radio power aligns with established mini-halo scaling relations.

Detection of polarized emission from the radio relics and the cluster core.

Abstract

Abell 3667 is among the most well-studied galaxy clusters in the Southern Hemisphere. It is known to host two giant radio relics and a head-tail radio galaxy as the brightest cluster galaxy. Recent work has suggested the additional presence of a bridge of diffuse synchrotron emission connecting the North-Western radio relic with the cluster centre. In this work, we present full-polarization observations of Abell 3667 conducted with the Karoo Array Telescope at 1.33 and 1.82 GHz. Our results show both radio relics as well as the brightest cluster galaxy. We use ancillary higher-resolution data to subtract the emission from this galaxy, revealing a localised excess, which we tentatively identify as a radio mini-halo. This mini-halo candidate has an integrated flux density of $67.2\pm4.9$ mJy beam$^{-1}$ at 1.37 GHz, corresponding to a radio power of P$_{\rm{1.4\,GHz}}=4.28\pm0.31\times10^{23}$ W Hz$^{-1}$, consistent with established trends in mini-halo power scaling.