Properties of Cluster Radio Emission
  Relevant studies of the non-thermal components of the intracluster medium are performed at radio wavelengths. A number of clusters, indeed, exhibits cluster-wide diffuse radio emission, which is indication of the existence of large scale magnetic fields and of relativistic electrons in the cluster volume. There is strong evidence that the presence of diffuse radio emission is related to cluster merger processes. The details of the halo-merger connection are discussed and a brief outline of current models of halo formation is presented. 
Luigina Feretti (IRA, Bologna, Italy)