The origin of the relationship between black hole mass and host galaxy bulge luminosity

TL;DR

This paper explains the tight correlation between black hole mass and galaxy bulge luminosity as a natural result of hierarchical galaxy mergers, without requiring feedback mechanisms.

Contribution

It demonstrates that the observed low scatter in the black hole mass-bulge luminosity relation arises from initial dispersion and merger-driven growth, challenging feedback-based explanations.

Findings

Scatter decreases with increasing luminosity

Hierarchical mergers explain the tight correlation

Feedback mechanisms are unnecessary for this relation

Abstract

There is a strong decrease in scatter in the black hole mass versus bulge luminosity relationship with increasing luminosity and very little scatter for the most luminous galaxies. It is shown that this is a natural consequence of the substantial initial dispersion in the ratio of black hole mass to total stellar mass and of subsequent galaxy growth through hierarchical mergers. "Fine-tuning" through feedback between black hole growth and bulge growth is neither necessary nor desirable.