ar X iv : a st ro - p h / 02 01 08 1 v 1 7 J an 2 00 2 On the black hole - bulge mass relation in active and inactive galaxies

New virial black-hole mass estimates are presented for a sample of 72 AGN covering three decades in optical luminosity. Using a model in which the AGN broad-line region (BLR) has a flattened geometry, we investigate the M bh − L bulge relation for a combined 90-object sample, consisting of the AGN plus a sample of 18 nearby inactive elliptical galaxies with dynamical black-hole mass measurements. It is found that, for all reasonable mass-to-light ratios, the M bh − L bulge relation is equivalent to a linear scaling between bulge and black-hole mass. The best-fitting normalization of the M bh − M bulge relation is found to be M bh = 0.0012M bulge , in agreement with recent black-hole mass studies based on stellar velocity dispersions. Furthermore, the scatter around the M bh − L bulge relation for the full sample is found to be significantly smaller than has been previously reported (∆ log M bh = 0.39 dex). Finally, using the nearby inactive elliptical galaxy sample alone, it is shown that the scatter in the M bh − L bulge relation is only 0.33 dex, comparable to that of the M bh − σ relation. These results indicate that reliable black-hole mass estimates can be obtained for high redshift galaxies.