The radio and X-ray correlation in a sample of hard X-ray selected AGN

Abstract

The accretion-ejection mechanism acting in Active Galactic Nuclei (AGN) is one of the main astrophysical open questions. A strong correlation between the nuclear 2-10 keV X-ray versus core radio luminosities suggests that the accretion flow and the radio source are strongly coupled both in radio-quietAGN and in radio-loudAGN.We approach this topic fromthe hard X-ray point of view by discussing the radio versus X-ray correlation in a complete sample of INTEGRAL AGN, selected between 20-40 keV. A strong correlation between the 20-100 keV and NVSS radio luminosities is found, which is more significant than the correlation of the 2-10 keV and radio luminosities. When computed for an optically selected sample of local AGN, the correlation slope is steeper with respect to the one obtained for the INTEGRAL AGN sample. These results indicate that the X-ray versus radio correlations hold also for relatively high luminosity AGN, suggesting that in efficient accretion systems the two source of emission are in someway connected.