The Self-Regulated Growth of Supermassive Black Holes

TL;DR

This paper uses simulations to show that supermassive black holes grow until feedback halts further accretion, following fundamental physical relations regardless of their galaxy's fueling mechanism, with some differences in structural host properties.

Contribution

It demonstrates that SMBHs follow a universal growth pattern driven by feedback, independent of fueling mechanisms, and highlights the fundamental nature of the black hole fundamental plane and binding energy correlations.

Findings

SMBHs follow the same BHFP and correlation with bulge binding energy across fueling mechanisms.

Growth halts when feedback unbinds local gas, reaching a critical mass.

SMBHs in pseudobulges and barred systems deviate from classical correlations.

Abstract

We present a series of simulations of the self--regulated growth of supermassive black holes (SMBHs) in galaxies via three different fueling mechanisms: major mergers, minor mergers, and disk instabilities. The SMBHs in all three scenarios follow the same black hole fundamental plane (BHFP) and correlation with bulge binding energy seen in simulations of major mergers, and observed locally. Furthermore, provided that the total gas supply is significantly larger than the mass of the SMBH, its limiting mass is not influenced by the amount of gas available or the efficiency of black hole growth. This supports the assertion that SMBHs accrete until they reach a critical mass at which feedback is sufficient to unbind the gas locally, terminating the inflow and stalling further growth. At the same time, while minor and major mergers follow the same projected correlations (e.g., the $M_{BH}-\sigma$ and Magorrian relations), SMBHs grown via disk instabilities do not, owing to structural differences between the host bulges. This finding is supported by recent observations of SMBHs in pseudobulges and bulges in barred systems, as compared to those hosted by classical bulges. Taken together, this provides support for the BHFP and binding energy correlations as being more "fundamental" than other proposed correlations in that they reflect the physical mechanism driving the co-evolution of SMBHs and spheroids.