Suppressing the cooling flows in massive galaxies with turbulent stirring

We investigate the cooling flow problem of massive galaxies with halo masses of 10^12 - 10^14 solar masses using high-resolution idealized, non-cosmological simulations with the FIRE-2 (Feedback In Realistic Environments) stellar feedback model. We find that various solutions proposed in the literature, including Type Ia supernovae, AGB winds, other stellar feedback, morphological quenching, magnetic fields, and cosmic ray feedback, do not suppress cooling flows. On the other hand, for the ~10^14 Msun halo, our toy model for AGN feedback, where we include turbulent stirring, does significantly reduce the cooling flow and quenches the galaxy with an energy input rate ∼ 10^43 erg/s . The run with turbulent stirring has higher ratios of cooling time to dynamical time (tcool/tdynamical) and cooling time to turbulent mixing time (tcool/tturb), consistent with the weaker cooling flow. On the contrary, if the same amount of energy is injected as thermal heat, it has a much weaker effect on the cooling flow.

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