Clusters of galaxies in radio

Abstract

Recent results on the radio emission from galaxy clusters are reviewed, with emphasis both on the radio galaxies and on the diffuse radio emission from the intracluster medium. We show that the formation of the tailed morphology in cluster radio galaxies is due to the effect of the cluster gaseous environment and of its large scale motions in merging clusters. From Chandra X-ray data, it has also become evident that the gas in the hot cluster atmospheres may be displaced by the relativistic plasma. The statistical characteristics of radio galaxies are briefly discussed, and are shown to be surprisingly similar for sources both inside and outside rich clusters. The study of diffuse radio sources originating from the intracluster medium (halos and relics) has presently become a major area of investigation. Halos and relics are detected in massive X-ray luminous clusters which are undergoing violent merger processes. The power of radio halos is correlated with the cluster X-ray luminosity and mass.