A radio minihalo in the extreme cool-core galaxy cluster RXCJ1504.1-0248

TL;DR

This paper reports the discovery of a radio minihalo in the luminous cool-core galaxy cluster RXCJ1504.1-0248, providing new insights into the origin of minihalos and their association with cluster core dynamics.

Contribution

It presents the first detection of a radio minihalo in one of the most luminous cool-core clusters, linking minihalo formation to core sloshing and turbulence.

Findings

Detected a 140 kpc radio minihalo in RXCJ1504.1-0248.

Identified two cold fronts indicating core sloshing.

Suggests minihalo origin is related to turbulence from sloshing.

Abstract

Aims. We report the discovery of a radio minihalo in RXCJ1504.1-0248, a massive galaxy cluster that has an extremely luminous cool core. To date, only 9 radio minihalos are known, thus the discovery of a new one, in one of the most luminous cool-core clusters, provides important information on this peculiar class of sources and sheds light on their origin. Methods. The diffuse radio source is detected using GMRT at 327 MHz and confirmed by pointed VLA data at 1.46 GHz. The minihalo has a radius of $\sim$140 kpc. A Chandra gas temperature map shows that the minihalo emission fills the cluster cool core and has some morphological similarities to it, as has been previously observed for other minihalos. Results. The Chandra data reveal two subtle cold fronts in the cool core, likely created by sloshing of the core gas, as observed in most cool-core clusters. Following previous work, we speculate that the origin of the minihalo is related to sloshing. Sloshing may result in particle acceleration by generating turbulence and/or amplifying the magnetic field in the cool core, leading to the formation of a minihalo.