Raining on Galaxies and Black Holes: Unifying the Micro and Macro Properties of AGN Feeding and Feedback

Dr. Massimo Gaspari (Princeton)

Feeding and feedback tied to supermassive black holes (SMBHs) play central role in the cosmic evolution of galaxies, groups, and clusters of galaxies. The self-regulated active galactic nucleus (AGN) cycle is matter of intense debate. I review key results of our numerical campaign to unveil how SMBHs are tightly coupled to the multiphase gaseous halos, linking the inner gravitational radius to the large Mpc scale and vice versa. Massively parallel magnetohydrodynamic simulations show the turbulent plasma halo radiatively cools via a top-down multiphase condensation rain of warm filaments and molecular clouds. The multiphase precipitation inherits the hot halo kinematics and thermodynamics, ultimately establishing a 'cosmic weather'. In the nuclear region, the recurrent collisions between the clouds and filaments promote angular momentum cancellation and boost the SMBH accretion rate through a mechanism known as Chaotic Cold Accretion (CCA). The CCA rapid variability triggers powerful AGN outflows, which quench the macro cooling flow and star formation, while preserving the atmospheres of galaxies, groups, and clusters in global thermal equilibrium throughout cosmic time. I highlight the key imprints of AGN feedback and feeding, such as bubbles, shocks, turbulence, and condensed structures, with a critical eye toward observational concordance, including the X-ray plasma, optical filaments, and radio molecular clouds.