Cusp-core transformations induced by AGN feedback in the progenitors of
  cluster galaxies
  In a recent study (Martizzi et al. 2012), we used cosmological simulations to
show that active galactic nuclei (AGN) feedback on the gas distribution in
clusters of galaxies can be important in determining the spatial distribution
of stars and dark matter in the central regions of these systems. The
hierarchical assembly of dark matter, baryons and black holes obscures the
physical mechanism behind the restructuring process. Here we use idealized
simulations to follow the response of a massive dark matter halo as we feed the
central black hole with a controlled supply of cold gas. This removes most of
the complexity taking place in the cosmological simulations that may have
biased our previous study. We confirm our previous results: gas heated and
expelled from the central regions of the halo by AGN feedback can return after
cooling; repeated cycles generate gravitational potential fluctuations
responsible for irreversible modifications of the dark matter mass profile. The
main result is the expulsion of large amounts of baryons and dark matter from
the central regions of the halo. According to the work presented here, outflow
induced fluctuations represent the only mechanism able to efficiently create
dark matter cores in clusters of galaxies.
