A Revised Calibration of the Virial Mass Estimator for Black Holes in Active Galaxies Based on Single-epoch Hβ Spectra

The masses of supermassive black holes in broad-line active galactic nuclei (AGNs) can be measured through reverberation mapping, but this method currently cannot be applied to very large samples or to high-redshift AGNs. As a practical alternative, one can devise empirical scaling relations, based on the correlation between broad-line region size and AGN luminosity and the relation between black hole mass and bulge stellar velocity dispersion, to estimate the virial masses of black holes from single-epoch spectroscopy. We present a revised calibration of the black hole mass estimator for the commonly used H$\beta$ emission line. Our new calibration takes into account the recent determination of the virial coefficient for pseudo and classical bulges.