Fueling, Winds, and Self-Regulation: SMBH Growth and Feedback from Cosmic Noon to the Local Universe with the FIRE simulations

Feedback from active galactic nuclei (AGN), powered by gas accretion onto supermassive black holes (SMBHs), is widely invoked as a key regulator of star formation in massive galaxies. However, the coupling between sub-kpc fueling, time-variable accretion, and multiphase outflows is hard to isolate observationally and difficult to capture in a single theoretical framework. High-resolution FIRE cosmological hydrodynamic simulations with a multiphase interstellar medium and explicit SMBH accretion and feedback models make it possible to follow these connections in time, from the gas supply in the circumgalactic medium (CGM) to nuclear inflow and the launching and impact of winds. In this presentation, I will summarize recent results focusing on three regimes that highlight the diversity of fueling and feedback across mass scale and cosmic time, from massive galaxies at their peak activity to Seyfert galaxies in the local universe. (1) I will first present a new nuclear fueling channel driving luminous quasars at cosmic noon based on the large pileup of gas in the inner CGM produced by a global galactic outflow that later reaccretes coherently onto the galaxy, resulting in significantly higher inflow rates than pre-outflow conditions that can directly supply the nuclear region and trigger a luminous quasar phase. (2) I will then show that the resulting powerful AGN-driven winds can carve central cavities and suppress star formation in massive galaxies at cosmic noon primarily by preventing gas accretion into the ISM rather than by ejecting the existing star-forming gas reservoir. At the same time, strong AGN wind–ISM interactions can locally compress gas and result in positive feedback, including the rapid formation of ultra-dense, off-center stellar clumps. (3) Finally, I will discuss fueling and feedback self-regulation in simulations of Seyfert-like galaxies at low redshift, where we identify recurrent cycles linking increased inflow toward the accretion disk, enhanced SMBH accretion, feedback-driven clearing of the nuclear region, and subsequent re-fueling on ~10–100 Myr timescales. Comparisons to the observed connection between AGN luminosity and nuclear gas deficit provide direct constraints on the characteristic spatial and temporal scales of SMBH self-regulation.