Self-regulated AGN feedback of light jets in cool-core galaxy clusters
  Heating from active galactic nuclei (AGN) is thought to stabilize cool-core
clusters, limiting star formation and cooling flows. We employ radiative
magneto-hydrodynamic (MHD) simulations to model light AGN jet feedback with
different accretion modes (Bondi-Hoyle-Lyttleton and cold accretion) in an
idealised Perseus-like cluster. Independent of the probed accretion model,
accretion efficiency, jet density and resolution, the cluster self-regulates
with central entropies and cooling times consistent with observed cool-core
clusters in this non-cosmological setting. We find that increased jet
efficiencies lead to more intermittent jet powers and enhanced star formation
rates. Our fiducial low-density jets can easily be deflected by orbiting cold
gaseous filaments, which redistributes angular momentum and leads to more
extended cold gas distributions and isotropic bubble distributions. In
comparison to our fiducial low momentum-density jets, high momentum-density jet
heats less efficiently and enables the formation of a persistent cold-gas disc
perpendicular to the jet that is centrally confined. Cavity luminosities
measured from our simulations generally reflect the cooling luminosities of the
intracluster medium (ICM) and correspond to averaged jet powers that are
relatively insensitive to short periods of low-luminosity jet injection. Cold
gas structures in our MHD simulations with low momentum-density jets generally
show a variety of morphologies ranging from discy to very extended filamentary
structures. In particular, magnetic fields are crucial to inhibit the formation
of unrealistically massive cold gas discs by redistributing angular momentum
between the hot and cold phases and by fostering the formation of elongated
cold filaments that are supported by magnetic pressure.
