Hard X-ray selected giant radio galaxies - I. The X-ray properties and radio connection.

We present the first broad-band X-raystudy of the nuclei of 14 hard X-rayselected giant radio galaxies, based both on the literature and on the analysis of archival X-raydata from NuSTAR, XMM-Newton, Swift and INTEGRAL. The X-rayproperties of the sources are consistent with an accretion-related X-rayemission, likely originating from an X-raycorona coupled to a radiatively efficient accretion flow. We find a correlation between the X-ray luminosityand the radio core luminosity, consistent with that expected for AGNs powered by efficient accretion. In most sources, the luminosityof the radio lobes and the estimated jet power are relatively low compared with the nuclear X-rayemission. This indicates that either the nucleus is more powerful than in the past, consistent with a restarting of the central engine, or that the giant lobes are dimmerdue to expansion losses.