Feedback from Reorienting AGN Jets
  [abridged] Aims: We test the effects of re-orienting jets from an active
galactic nucleus (AGN) on the intracluster medium in a galaxy cluster
environment with short central cooling time. We investigate appearance and
properties of the resulting cavities, and the efficiency of jets in providing
near-isotropic heating to the cooling cluster core.
  Methods: We use numerical simulations to explore four models of jets over
several active/inactive cycles. We keep the jet power and duration fixed,
varying only the jet angle prescription. We track the total energy of the
intracluster medium (ICM) in the cluster core over time, and the fraction of
the jet energy transferred to the ICM, paying attention to where the energy is
deposited. We also compare synthetic X-ray images of the simulated cluster to
actual observations.
  Results: Jets whose re-orientation is minimal ($\lesssim 20^{\circ}$)
typically produce conical structures of interconnected cavities, with the
opening angle of the cones being $\sim 15-20^{\circ}$, extending to $\sim 300$
kpc from the cluster centre. Such jets transfer about $60\%$ of their energy to
the ICM, yet they are not very efficient at heating the cluster core, as the
jet energy is deposited further out. Jets that re-orient by $\gtrsim
20^{\circ}$ generally produce multiple pairs of detached cavities. Although
smaller, these cavities are inflated within the central 50~kpc and are more
isotropically distributed, resulting in more effective heating of the core.
Such jets, over few hundreds Myr, can deposit up to $80\%$ of their energy
where it is required. Consequently, these models come the closest to an
heating/cooling balance and to mitigating runaway cooling of the core, even
though all models have identical power/duration profiles. Additionally, the
corresponding synthetic X-ray images exhibit structures closely resembling
those seen in real cool-core clusters.
