Speaker
Description
In this talk, I will show how the study of AGN incidence distributions is a powerful tool to understand the global energetics of AGN feedback. We use the complete, spectroscopic GAMA09 survey (z<0.4) to measure the fraction of galaxies hosting radio and X-ray AGN, defined using LOFAR and eROSITA data, as functions of mass-scaled power indicators. We recover the previously found mass-invariant triggering and fueling mechanisms in the incidence of X-ray AGN as a function of λEdd (∝ X-ray luminosity/stellar mass). However, the story is more perplexing in the case of radio AGN, as the incidence of radio AGN as a function of mass-scaled kinetic power (∝ jet power/stellar mass) shows a mass and jet power dependence. In fact, we find that radio morphology (compact vs complex) strongly affects the radio AGN incidence. These differences translate directly to the ways in which these AGN feed back energy to their host galaxies and halos. We quantify this by computing, for the first time, the average jet power for the population of massive galaxies as a function of stellar mass and radio morphology. We show that jet kinetic feedback dominates over any plausible inventory of radiatively-driven feedback for massive galaxies in the local universe. We also show, by comparing the average jet kinetic energy to the galaxy/halo binding energy, that radio AGN cannot fully unbind their host galaxies nor host halos. However, they have enough energy to impact the global thermodynamical heating and cooling balance in small halos and significantly contribute to offsetting local cooling flows in even the most massive clusters cores. Importantly, this work provides a clear observational benchmark to calibrate AGN feedback simulations. Lastly, since much of our knowledge about AGN accretion and feedback has been limited to massive galaxies, I give a brief outlook on how eROSITA can be used to study the low-mass regime, including X-ray emitting intermediate mass black holes in local dwarf galaxies.
