SMBH accretion & mergers: removing the symmetries

TL;DR

This paper reviews recent advances in understanding SMBH accretion and mergers by removing symmetry assumptions, revealing complex behaviors that impact black hole growth, spin, and merger dynamics.

Contribution

It introduces a framework that relaxes symmetry assumptions in SMBH accretion models, enabling exploration of more realistic and diverse phenomena.

Findings

Rapid infall due to angular momentum cancellation

Lower SMBH spins facilitate faster mass growth

Suppressed gravitational recoil in mergers

Abstract

We review recent progress in studying accretion flows on to supermassive black holes (SMBH). Much of this removes earlier assumptions of symmetry and regularity, such as aligned and prograde disc rotation. This allows a much richer variety of effects, often because cancellation of angular momentum allows rapid infall. Potential applications include lower SMBH spins allowing faster mass growth and suppressing gravitational-wave reaction recoil in mergers, gas-assisted SMBH mergers, and near-dynamical accretion in galaxy centres.