Do radio mini-halos and gas heating in cool-core clusters have a common origin?

TL;DR

This study investigates whether radio mini-halos and gas heating in cool-core galaxy clusters share a common origin, finding a correlation between radio luminosity and cooling flow power that supports a linked energetic process.

Contribution

It provides evidence that radio mini-halos and gas heating may originate from the same turbulence-driven mechanism in cool-core clusters, based on a homogeneous analysis of X-ray data.

Findings

A quasi-linear correlation between mini-halo radio luminosity and cooling flow power.

Energetic viability of a common origin for mini-halos and gas heating.

Mini-halos trace regions with magnetic fields much stronger than 0.5 μG.

Abstract

In this letter we present a study of the central regions of cool-core clusters hosting radio mini-halos, which are diffuse synchrotron sources extended on cluster-scales surrounding the radio-loud brightest cluster galaxy. We aim to investigate the interplay between the thermal and non-thermal components in the intra-cluster medium in order to get more insights into these radio sources, whose nature is still unclear. It has recently been proposed that turbulence plays a role for heating the gas in cool cores. By assuming that mini-halos are powered by the same turbulence, we expect that the integrated radio luminosity of mini-halos, $\nu P_{\nu}$, depends on the cooling flow power, $P_{\rm CF}$, which in turn constrains the energy available for the non-thermal components and emission in the cool-core region. We carried out a homogeneous re-analysis of X-ray Chandra data of the largest sample of cool-core clusters hosting radio mini-halos currently available ($\sim$ 20 objects), finding a quasi-linear correlation, $\nu P_{\nu} \propto P_{\rm CF}^{0.8}$. We show that the scenario of a common origin of radio mini-halos and gas heating in cool-core clusters is energetically viable, provided that mini-halos trace regions where the magnetic field strength is $B \gg 0.5\, \mu$G .