The Dance of Heating and Cooling in Galaxy Clusters: 3D Simulations of
  Self-Regulated AGN Outflows
  It is now widely accepted that heating processes play a fundamental role in
galaxy clusters, struggling in an intricate but fascinating `dance' with its
antagonist, radiative cooling. Last generation observations, especially X-ray,
are giving us tiny hints about the notes of this endless ballet. Cavities,
shocks, turbulence and wide absorption-lines indicate the central active
nucleus is injecting huge amount of energy in the intracluster medium. However,
which is the real dominant engine of self-regulated heating? One of the model
we propose are massive subrelativistic outflows, probably generated by a wind
disc or just the result of the entrainment on kpc scale by the fast radio jet.
Using a modified version of AMR code FLASH 3.2, we explored several feedback
mechanisms which self-regulate the mechanical power. Two are the best schemes
that answer our primary question, id est quenching cooling flow and at the same
time preserving a cool core appearance for a long term evolution (7 Gyr): one
more explosive (with efficiencies 0.005 - 0.01), triggered by central cooled
gas, and the other gentler, ignited by hot gas Bondi accretion (with efficiency
0.1). These three-dimensional simulations show that the total energy injected
is not the key aspect, but the results strongly depend on how energy is given
to the ICM. We follow the dynamics of best model (temperature, density, SB maps
and profiles) and produce many observable predictions: buoyant bubbles,
ripples, turbulence, iron abundance maps and hydrostatic equilibrium deviation.
We present a deep discussion of merits and flaws of all our models, with a
critical eye towards observational concordance.
