Simulating the effect of AGN feedback on the metal enrichment of galaxy
  clusters
  We present a study of the effect of AGN feedback on metal enrichment and
thermal properties of the intracluster medium (ICM) in hydrodynamical
simulations. The cosmological simulations are performed for a set of clusters
using a version of the TreePM-SPH Gadget code that follows chemo-dynamical
evolution by accounting for metal enrichment by different stellar populations.
Besides runs not including any efficient form of energy feedback, we carry out
simulations including: (i) kinetic feedback in the form of galactic winds
triggered by supernova explosions; (ii) AGN feedback from gas accretion onto
super-massive black holes (BHs); (iii) AGN feedback in which a 'radio mode' is
included. We find that AGN feedback is able to quench star formation in the
brightest cluster galaxies at z<4 and provides correct temperature profiles in
the central regions of galaxy groups. However, its effect is not sufficient to
create cool cores in massive clusters. AGN feedback creates a widespread
enrichment in the outskirts of clusters, thanks to its efficiency in displacing
enriched gas from galactic halos to the inter-galactic medium at relatively
high redshift. Iron abundance profiles are in better agreement with
observations, with a more pristine enrichment of the ICM around and beyond the
cluster virial regions. From the pattern of the relative abundances of Silicon
and Iron, we conclude that a significant fraction of ICM enrichment in
simulations is contributed by a diffuse population of intra-cluster stars. Our
simulations also predict that profiles of Z_Si/Z_Fe abundance ratio do not
increase at least out to 0.5 R_vir. Our results clearly show that different
sources of energy feedback leave distinct imprints in the enrichment pattern of
the ICM, that are more evident when looking at cluster external regions.
