Observations at 610 MHz of radio halos in clusters of galaxies

In a search for diffuse radio sources such as that in the Coma cluster, 610-MHz observations of 32 galaxy clusters have been made with the Green Bank 300-foot (91-m) telescope. For 20 of these clusters the interferometric observations available at the same frequency made it possible to subtract any small high-brightness sources from the data. No Coma-like halos in any other nearby clusters were detected, although some brighter diffuse sources are visible in the interferometric maps of more distant clusters. From the continuity of morphology of the various cluster sources it is suggested that the halo sources are fossils of extended radio galaxies such as the head-tail sources