The Role of Turbulence in AGN Self-Regulation in Galaxy Clusters
  Cool cores of galaxy clusters are thought to be heated by low-power active
galactic nuclei (AGN), whose accretion is regulated by feedback. However, the
interaction between the hot gas ejected by the AGN and the ambient intracluster
medium is extremely difficult to simulate, as it involves a wide range of
spatial scales and gas that is Rayleigh-Taylor (RT) unstable. Here we use a
subgrid model for RT-driven turbulence to overcome these problems and present
the first observationally-consistent hydrodynamical simulations of AGN
self-regulation in galaxy clusters. For a wide range of parameter choices the
cluster in our three-dimensional simulations regulates itself for at least
several Gyrs years. Heating balances cooling through a string of outbreaks with
a typical recurrence time of approximately 80 Myrs, a timescale that depends
only on the global cluster properties.
