New black-hole mass estimates are presented for a sample of 72 AGN covering three decades in optical luminosity .
Using a sub-sample of Seyfert galaxies , which have black-hole mass estimates from both reverberation mapping and stellar velocity dispersions , we investigate the geometry of the AGN broad-line region ( BLR ) .
It is demonstrated that a model in which the orbits of the line-emitting material have a flattened geometry is favoured over randomly orientated orbits .
Using this model 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 } = 0.0012 M _ { 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 ( \Delta \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 } - \sigma relation .
These results indicate that reliable black-hole mass estimates can be obtained for high redshift galaxies .