Gravitational torque-driven black hole growth and feedback in cosmological simulations

TL;DR

This study uses cosmological simulations with a self-consistent black hole growth and feedback model to explore the primary role of gravitational torques in black hole and galaxy co-evolution, showing feedback effects are secondary.

Contribution

It introduces a simulation model that captures angular momentum transport via gravitational torques and demonstrates their dominant role in black hole-host galaxy scaling relations.

Findings

Black hole-host scaling relations are weakly affected by feedback.

Gravitational torques regulate black hole growth and galaxy co-evolution.

Kinetic feedback impacts intergalactic medium properties.

Abstract

We investigate black hole-host galaxy scaling relations in cosmological simulations with a self-consistent black hole growth and feedback model. The sub-grid accretion model captures the key scalings governing angular momentum transport from galactic scales down to parsec scales, while our kinetic feedback implementation enables the injection of outflows with properties chosen to match observed nuclear outflows. We show that "quasar mode" feedback can have a large impact on the thermal properties of the intergalactic medium and the growth of galaxies and massive black holes for kinetic feedback efficiencies as low as 0.1% relative to the bolometric luminosity. Nonetheless, our simulations suggest that the black hole-host scaling relations are only weakly dependent on the effects of black hole feedback on galactic scales, owing to feedback suppressing the growth of galaxies and massive black holes by a similar amount. In contrast, the rate at which gravitational torques feed the central black hole relative to the host galaxy star formation rate governs the slope and normalization of the black hole-host correlations. Our results suggest that a common gas supply regulated by gravitational torques is the primary driver of the observed co-evolution of black holes and galaxies.