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We present an analysis of the 2-10 keV X-ray emission associated with the active galactic nuclei (AGNs) in brightest cluster galaxies (BCGs). Our sample consists of 32 BCGs that lie in highly X-ray luminous cluster of galaxies (L_X-ray (0.1-2.4 keV) > 3*10^44 erg/s) in which AGN-jetted outflows are creating and sustaining clear Xray cavities. Our sample covers the redshift range 0 < z < 0.6 and reveals strong evolution in the nuclear X-ray luminosities, such that the black holes in these systems have become on average at least 10 times fainter over the last 5 Gyrs. Mindful of potential selection effects, we propose two possible scenarios to explain our results: 1) either that the AGNs in BCGs with X-ray cavities are steadily becoming fainter, or more likely, 2) that the fraction of these BCGs with radiatively efficient nuclei is decreasing with time from roughly 60 per cent at z=0.6 to 30 per cent at z=0.1. Based on this strong evolution, we predict that a significant fraction of BCGs in z=1 clusters may host quasars at their centres, potentially complicating the search for such clusters at high redshift. In analogy with black-hole binaries and based on the observed Eddington ratios of our sources, we further propose that the evolving AGN population in BCGs with X-ray cavities may be transiting from a canonical low/hard state, analogous to that of X-ray binaries, to a quiescent state over the last 5 Gyrs.
We report on the results of a Chandra search for evidence of triggered nuclear activity within the Cl0023+0423 four-way group merger at z ~ 0.84. The system consists of four interacting galaxy groups in the early stages of hierarchical cluster format
During the performance verification phase of the SRG/eROSITA telescope, the eROSITA Final Equatorial-Depth Survey (eFEDS) has been carried out. It covers a 140 deg$^2$ field located at 126$^circ <$ R.A. $< 146^circ$ and -3$^circ <$ Dec. $< +6^circ$ w
The ISM evolution of elliptical galaxies experiencing feedback from accretion onto a central black hole was studied recently with high-resolution 1D hydrodynamical simulations including radiative heating and pressure effects, a RIAF-like radiative ef
We examine unresolved nuclear X-ray sources in 57 brightest cluster galaxies to study the relationship between nuclear X-ray emission and accretion onto supermassive black holes (SMBHs). The majority of the clusters in our sample have prominent X-ray
This paper presents the first measurement of the radio luminosity function of jet-mode (radiatively-inefficient) radio-AGN out to z=1, in order to investigate the cosmic evolution of radio-AGN feedback. Eight radio source samples are combined to prod