Relic sources and diffuse cluster radio emission

Late evolution of an extended radio source is studied in the context of a simple model of magnetically driven expansion. The evolving radio spectrum is calculated by accounting for synchrotron, Compton, and expansion energy losses of relativistic electrons in the varying magnetic field of the source. We estimate the Compton X-ray fluxes of the relics 0924+30 and 1253+275, and conclude that the latter source is likely to be a dominant component of the high-energy flux from the Coma region, if measured by a detector with a large field of view (such as the OSSE on board the Compton Gamma Ray Observatory). We briefly discuss the possibility that steep-spectrum relics and diffuse radio sources in clusters have a common origin.