2018ApJ...864..146B

We have utilized high-resolution optical Hubble Space Telescope images and deep, ground-based near-infrared images to examine the host galaxies of 37 active galactic nuclei (AGNs) with reverberation-based black hole masses. Using two-dimensional image decompositions, we have separated the host galaxy from the bright central AGN, allowing a re-examination of the M_BH–L_bulge and M_BH–L_galaxy relationships and the M_BH–M_bulge and M_BH–M_stars relationships using V-H color to constrain the stellar mass-to-light ratio. We find clear correlations for all of these scaling relationships, and the best-fit correlations are generally in good agreement with the sample of early-type galaxies with M_BH from dynamical modeling and the sample of megamasers. We also find good agreement with the expectations from the Illustris simulations, although the agreement with other simulations is less clear because of the different black hole mass ranges that are probed. M_BH–L_bulge is found to have the least scatter, and is therefore the best predictor of M_BH among the relationships examined here. Large photometric surveys that rely on automated analysis and forego bulge-to-disk decompositions will achieve more accurate M_BH predictions if they rely on M_BH–M_stars rather than M_BH–L_galaxy. Finally, we have examined M_BH/M_stars and find a clear trend with black hole mass but not galaxy mass. This trend is also exhibited by galaxies with M_BH from dynamical modeling and megamaser galaxies, as well as simulated galaxies from Illustris, rising from ∼0.01% at 10⁶ M_☉ to ∼1.0% at 10¹⁰ M_☉. This scaling should be taken into account when comparing galaxy samples that are not matched in M_BH.