Kinetic AGN Feedback Effects on Cluster Cool Cores Simulated using SPH
  We implement novel numerical models of AGN feedback in the SPH code GADGET-3,
where the energy from a supermassive black hole (BH) is coupled to the
surrounding gas in the kinetic form. Gas particles lying inside a bi-conical
volume around the BH are imparted a one-time velocity (10,000 km/s) increment.
We perform hydrodynamical simulations of isolated cluster (total mass 10^14 /h
M_sun), which is initially evolved to form a dense cool core, having central
T<10^6 K. A BH resides at the cluster center, and ejects energy. The
feedback-driven fast wind undergoes shock with the slower-moving gas, which
causes the imparted kinetic energy to be thermalized. Bipolar bubble-like
outflows form propagating radially outward to a distance of a few 100 kpc. The
radial profiles of median gas properties are influenced by BH feedback in the
inner regions (r<20-50 kpc). BH kinetic feedback, with a large value of the
feedback efficiency, depletes the inner cool gas and reduces the hot gas
content, such that the initial cool core of the cluster is heated up within a
time 1.9 Gyr, whereby the core median temperature rises to above 10^7 K, and
the central entropy flattens. Our implementation of BH thermal feedback (using
the same efficiency as kinetic), within the star-formation model, cannot do
this heating, where the cool core remains. The inclusion of cold gas accretion
in the simulations produces naturally a duty cycle of the AGN with a
periodicity of 100 Myr.
