Precessing AGN Jets, Bubbles and Cooling Flows
  Several galaxy clusters are known to present multiple and misaligned pairs of
cavities seen in X-rays, as well as twisted kiloparsec-scale jets at radio
wavelengths. It suggests that the AGN precessing jets play a role in the
formation of the misaligned bubbles. Also, X-ray spectra reveal that typically
these systems are also able to supress cooling flows, predicted theoretically.
The absence of cooling flows in galaxy clusters has been a mistery for many
years since numerical simulations and analytical studies suggest that AGN jets
are highly energetic, but are unable to redistribute it at all directions. We
performed 3D hydrodynamical simulations of the interaction between a precessing
AGN jet and the warm intracluster medium plasma, which dynamics is coupled to a
NFW dark matter gravitational potential. Radiative cooling has been taken into
account and the cooling flow problem was studied. We found that precession is
responsible for multiple pairs of bubbles, as observed. The misaligned bubbles
rise up to scales of tens of kiloparsecs, where the thermal energy released by
the jets are redistributed. After $\sim 150$ Myrs, the temperature of the gas
within the cavities is kept of order of $\sim 10^7$ K, while the denser plasma
of the intracluster medium at the central regions reaches $T \sim 10^5$ K. The
existence of multiple bubbles, at diferent directions, result in an integrated
temperature along the line of sight much larger than the simulations of
non-precessing jets. This result is in agreement with the observations. The
simulations reveal that the cooling flows cessed $\sim 50 - 70$ Myr after the
AGN jets are started.
