Paper detail

Black Holes and Hosts of Active and Quiescent Galaxies: I. The Black Hole-Bulge Relation revisited

Massive Black Holes detected in the centers of many nearby galaxies show an approximately linear relation with the luminosity of the host bulge, with the black hole mass being 0.001-0.002 of the bulge mass. Previous work suggested that black holes of active (Seyfert 1) galaxies follow a similar relation, but apparently with a significantly lower value of $M_{\rm BH}/M_{\rm bulge}$ (Wandel 1999). New data show that this difference was mainly due to overestimating the black hole mass in quiescent galaxies and overestimating the bulge magnitude of Seyfert galaxies. Using new and updated data we show that AGNs (Seyfert galaxies and quasars) follow the same BH-bulge relation as ordinary (inactive) galaxies. We derive the BH-bulge relation for a sample of 55 AGNs and 35 quiescent galaxies, finding that broad line AGNs have an average black hole/bulge mass fraction of $\sim 0.0015$ with a strong correlation (Mbh ~ Lbulge^{0.9\pm 0.16}). This BH-bulge relation is consistent with the BH-bulge relation of quiescent galaxies and much tighter than previous results. Narrow line AGNs appear to have a lower ratio, Mbh/Mbulge ~ 10^{-4}-10^{-3}. We find this to be a more general feature, the BH/bulge ratio in AGNs being inversely correlated with the emission-line width, implying a strong linear relation between the size of the broad emission line region and the luminosity of the bulge. Finally, combining AGNs with observed and estimated stellar velocity dispersion, we find a significant correlation (Mbh ~ v^{3.5-5}), consistent with that of quiescent galaxies.