Host Galaxy Bulge Predictors of Supermassive Black Hole Mass

TL;DR

This study identifies the bulge gravitational binding energy as a strong predictor of supermassive black hole mass, comparable to velocity dispersion, using a sample of 23 nearby galaxies and improved mass-to-light ratios.

Contribution

It introduces bulge gravitational binding energy as a novel and effective predictor of SMBH mass, with reduced scatter using advanced spectroscopy and photometry.

Findings

Strong correlation between SMBH mass and bulge gravitational binding energy.

Energy predictor has similar predictive power as velocity dispersion.

Improved mass-to-light ratios reduce scatter in the SMBH mass prediction.

Abstract

A variety of host galaxy (bulge) parameters are examined in order to determine their predictive power in ascertaining the masses of the supermassive black holes (SMBH) at the centers of the galaxies. Based on a sample of 23 nearby galaxies, comprised of both elliptical galaxies and spiral/lenticular bulges, we identify a strong correlation between the bulge gravitational binding energy ($E_g$), as traced by the stellar light profile, and the SMBH mass ($M_{\bullet}$), such that $M_{\bullet} \propto E_g^{0.6}$. The scatter about the relationship indicates that this is as strong a predictor of $M_{\bullet}$ as the velocity dispersion ($\sigma$), for the elliptical galaxy subsample. Improved mass-to-light ratios, obtained with IFU spectroscopy and I-band photometry by the SAURON group, were used for those sample galaxies where available, resulting in an energy predictor with the same slope, but with reduced scatter. Alternative $M_{\bullet}$ predictors such as the gravitational potential and the bulge mass are also explored, but these are found to be inferior when compared with both the bulge gravitational binding energy and bulge velocity dispersion predictors, for the full galaxy sample.