Spin-driven jet feedback in idealized simulations of galaxy groups and clusters

Abstract

We implement a black hole spin evolution and jet feedback model into SWIFT, a smoothed particle hydrodynamics code. The jet power is determined self-consistently assuming that the black hole accretion rate is equal to the Bondi rate (i.e. the accretion efficiency is 100 per cent), and using a realistic, spin-dependent efficiency. The jets are launched along the spin axis of the black hole, resulting in natural reorientation and precession. We apply the model to idealized simulations of galaxy groups and clusters, finding that jet feedback successfully quenches gas cooling and star formation in all systems. Our group-size halo (M200 = 1013 M⊙) is quenched by a strong jet episode triggered by a cooling flow, and it is kept quenched by a low-power jet fed from hot halo accretion. In more massive systems (M200 ≳ 1014 M⊙), hot halo accretion is insufficient to quench the galaxies, or to keep them quenched after the first cooling episode. These galaxies experience multiple episodes of gas cooling, star formation, and jet feedback. In the most massive galaxy cluster that we simulate (M200 = 1015 M⊙), we find peak cold gas masses of 1010 M⊙ and peak star formation rates of a few times 100 M⊙yr−1⁠. These values are achieved during strong cooling flows, which also trigger the strongest jets with peak powers of 1047ergs−1⁠. These jets subsequently shut off the cooling flows and any associated star formation. Jet-inflated bubbles draw out low-entropy gas that subsequently forms dense cooling filaments in their wakes, as seen in observations.