Radio emission in clusters and connection to X-ray emission

TL;DR

This paper reviews the connection between diffuse radio sources in galaxy clusters and their X-ray emissions, highlighting non-thermal processes, magnetic fields, and the insights gained from recent observations and models.

Contribution

It synthesizes recent observational and theoretical advances in understanding the non-thermal phenomena in galaxy clusters, emphasizing the link between radio and X-ray emissions.

Findings

Diffuse radio sources indicate relativistic particles and magnetic fields in clusters.

X-ray emissions provide insights into thermal and non-thermal processes.

Inverse Compton X-ray emission reveals energy density of radio-emitting particles.

Abstract

The most spectacular aspect of cluster radio emission is represented by the large-scale diffuse radio sources, which cannot be obviously associated with any individual galaxy. These sources demonstrate the existence of relativistic particles and magnetic fields in the cluster volume, thus indicating the presence of non-thermal processes in the hot intracluster medium. The knowledge of the properties of these sources has increased significantly in recent years, owing to sensitive radio images and to the development of theoretical models. An important piece of information on the origin and evolution of these sources can be obtained by the cluster X-ray emission of thermal origin, and by its relation to the radio emission. Moreover, non-thermal X-ray emission of inverse Compton origin gives direct information on the energy density of radio emitting particles and the intensity of magnetic field.