A Comprehensive Study of the Radio Properties of Brightest Cluster Galaxies

TL;DR

This study analyzes the radio properties of Brightest Cluster Galaxies across multiple clusters, decomposing their radio emissions into core and non-core components, and explores how these relate to cluster environment and emission lines.

Contribution

It provides a comprehensive multi-frequency radio analysis of BCGs, linking radio spectral components to cluster properties and emission line activity, which is a novel detailed decomposition approach.

Findings

Line-emitting BCGs host more powerful radio sources.

Core components correlate with optical emission lines.

X-ray cavity power relates to radio emission in line-emitting clusters.

Abstract

We examine the radio properties of the Brightest Cluster Galaxies (BCGs) in a large sample of X-ray selected galaxy clusters comprising the Brightest Cluster Sample (BCS), the extended BCS (eBCS) and ROSAT-ESO Flux Limited X-ray (REFLEX) cluster catalogues. We have multi-frequency radio observations of the BCG using a variety of data from the Australia Telescope Compact Array (ATCA), Jansky Very Large Array (VLA) and Very Long Baseline Array (VLBA) telescopes. The radio spectral energy distributions (SEDs) of these objects are decomposed into a component attributed to on-going accretion by the active galactic nuclei (AGN) that we refer to as the 'core', and a more diffuse, ageing component we refer to as the 'non-core'. These BCGs are matched to previous studies to determine whether they exhibit emission lines (principally H-alpha), indicative of the presence of a strong cooling cluster core. We consider how the radio properties of the BCGs vary with cluster environmental factors. Line emitting BCGs are shown to generally host more powerful radio sources, exhibiting the presence of a strong, distinguishable core component in about 60% of cases. This core component more strongly correlates with the BCG's [OIII]5007A line emission. For BCGs in line-emitting clusters, the X-ray cavity power correlates with both the extended and core radio emission, suggestive of steady fuelling of the AGN over bubble-rise time-scales in these clusters.