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

TL;DR

This study investigates the X-ray and radio properties of 14 giant radio galaxies, revealing correlations indicative of efficient accretion and suggesting possible engine restarting or lobe dimming effects.

Contribution

First broad-band X-ray analysis of giant radio galaxy nuclei, linking X-ray and radio emissions to accretion processes and jet activity.

Findings

X-ray emission consistent with accretion-related corona

Correlation between X-ray and radio core luminosities

Nuclear X-ray luminosity exceeds lobe luminosity in most sources

Abstract

We present the first broad-band X-ray study of the nuclei of 14 hard X-ray selected giant radio galaxies, based both on the literature and on the analysis of archival X-ray data from NuSTAR, XMM-Newton, Swift and INTEGRAL. The X-ray properties of the sources are consistent with an accretion-related X-ray emission, likely originating from an X-ray corona coupled to a radiatively efficient accretion flow. We find a correlation between the X-ray luminosity and the radio core luminosity, consistent with that expected for AGNs powered by efficient accretion. In most sources, the luminosity of the radio lobes and the estimated jet power are relatively low compared with the nuclear X-ray emission. 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 dimmer due to expansion losses.