On the origin and acceleration of cosmic rays: Cooling flow clusters and AGN hosts

TL;DR

This study investigates the presence of radio relics and halos in galaxy clusters, focusing on AGN hosts in cooling flow clusters, and finds no such features in the examined sample, providing insights into cosmic ray acceleration.

Contribution

It offers new observational analysis of radio relics and halos in specific galaxy clusters, linking AGN activity and cluster environments to cosmic ray acceleration mechanisms.

Findings

No relics or halos found in the examined clusters

Radio bubbles in AGN hosts may influence cosmic ray confinement

Results suggest limited occurrence of relics/halos in cooling flow clusters

Abstract

We are looking for radio `relics' and `halos' in an X-ray selected sample of clusters of galaxies. These radio features are not a product of the Active Galactic Nuclei (AGN)-mechanism, but more likely are associated with past cluster merger events. AGN hosts of cooling flow clusters contain particle bubbles that show non-thermal radio emission. These bubbles could explain the presence of radio relics and halos if they can restrict cosmic rays efficiently. Intracluster magnetic fields and cluster environments can reveal the acceleration mechanisms of cosmic rays. Using radio/X-ray data and analytical methods we examine three AGN hosts out of our 70 clusters, namely Hercules A, 3C310 and 3C388. We found that none of these clusters contain relics and/or halos.