The growth of supermassive black holes in pseudo-bulges, classical bulges and elliptical galaxies

TL;DR

This study analyzes the distribution and growth of supermassive black holes across different galaxy types, revealing that elliptical galaxies host the majority of black hole mass and that structural differences affect mass relation estimates.

Contribution

It provides a detailed breakdown of black hole mass distribution among galaxy types and highlights the impact of structural dissimilarities on mass relation estimates.

Findings

55% of black hole mass in ellipticals

41% in classical bulges

4% in pseudo-bulges

Abstract

Using results from structural analysis of a sample of nearly 1000 local galaxies from the Sloan Digital Sky Survey, we estimate how the mass in central black holes is distributed amongst elliptical galaxies, classical bulges and pseudo-bulges, and investigate the relation between their stellar masses and central stellar velocity dispersion sigma. Assuming a single relation between elliptical galaxy/bulge mass, M_Bulge, and central black hole mass, M_BH, we find that 55^{+8}_{-4} per cent of the mass in black holes in the local universe is in the centres of elliptical galaxies, 41^{+4}_{-2} per cent in classical bulges and 4^{+0.9}_{-0.4} per cent in pseudo-bulges. We find that ellipticals, classical bulges and pseudo-bulges follow different relations between their stellar masses and sigma, and the most significant offset occurs for pseudo-bulges in barred galaxies. This structural dissimilarity leads to discrepant black hole masses if single M_BH-M_Bulge and M_BH-sigma relations are used. Adopting relations from the literature, we find that the M_BH-sigma relation yields an estimate of the total mass density in black holes that is roughly 55 per cent larger than if the M_BH-M_Bulge relation is used.