Black Hole Mass Scaling Relations for Early-type Galaxies. I. M BH –M *, sph and M BH –M *,gal

Abstract

Analyzing a sample of 84 early-type galaxies (ETGs) with directly measured supermassive black hole masses—nearly doubling the sample size of such galaxies with multicomponent decompositions—a symmetric linear regression on the reduced (merger-free) sample of 76 galaxies reveals with a total scatter of Δ rms  = 0.52 dex in the direction. Importantly, however, we discover that the ES/S0-type galaxies with disks are offset from the E-type galaxies by more than a factor of ten in their ratio, with ramifications for formation theories, simulations, and some virial factor measurements used to convert AGN virial masses into M BH . Separately, each population follows a steeper relation with slopes of 1.86 ± 0.20 and 1.90 ± 0.20, respectively. The offset mass ratio is mainly due to the exclusion of the disk mass, with the two populations offset by only a factor of two in their ratio in the M BH – diagram where and dex depending on the sample. For , we detect no significant bend nor offset in either the M BH – or M BH – relations due to barred versus non-barred, or core-Sérsic versus Sérsic, ETGs. For reference, the ensemble of late-type galaxies (which invariably are Sérsic galaxies) follow M BH – and M BH – relations with slopes equal to 2.16 ± 0.32 and 3.05 ± 0.70, respectively. Finally, we provide some useful conversion coefficients, υ , accounting for the different stellar mass-to-light ratios used in the literature, and we report the discovery of a local, compact massive spheroid in NGC 5252.