The black-hole masses of Seyfert galaxies and quasars

The central black-hole masses of a sample of 30 luminous quasars are estimated using Hβ fwhm measurements from a combination of new and previously-published nuclear spectra. The quasar black-hole mass estimates are combined with reverberationmapping measurements for a sample of Seyfert galaxies (Wandel, Peterson & Malkan 1999) in order to study AGN black-hole masses over a wide range in nuclear luminosity. The link between bulge luminosity and black-hole mass is investigated using two-dimensional disc/bulge decompositions of the host-galaxy images, the vast majority of which are high resolution hst observations. It is found that black-hole mass and bulge luminosity are well correlated and follow a relation consistent with that expected if black-hole and bulge mass are directly proportional. Contrary to the results of Wandel (1999) no evidence is found that Seyfert galaxies follow a different Mbh − Mbulge relation to quasars. However, the black-hole mass distributions of the radio-loud and radio-quiet quasar sub-samples are found to be significantly different, with the median black-hole mass of the radio-loud quasars a factor of three larger than their radio-quiet counterparts. Finally, utilizing the elliptical galaxy fundamental plane to provide stellar velocity dispersion estimates, a comparison is performed between the virial Hβ black-hole mass estimates and those of the Mbh−σ correlations of Gebhardt et al. (2000a) and Merritt & Ferrarese (2000). With the disc geometry of the broad-line region adopted in this paper, the virial Hβ black-hole masses indicate that the correct normalization of the black-hole vs. bulge mass relation is Mbh ≃ 0.0025Mbulge, while the standard assumption of purely random broad-line velocities leads to Mbh ≃ 0.0008Mbulge. The normalization of Mbh ≃ 0.0025Mbulge provided by the disc model is in remarkably good agreement with that inferred for our quasar sample using the (completely independent) Mbh − σ correlations.