Black Holes and Hosts of Active Galactic Nuclei: I. the Black Hole-bulge Relation Revisited

Massive Black Holes detected by in the centers of many nearby galaxies show an approximately linear relation with the luminosity of the host bulge, inferring the black hole has a mass of 0.001-0.002 of the bulge. Previous work suggested that black holes of active (Seyfert 1) galaxies follow a similar relation, but apparently with a significantly lower value of MBH/Mbulge (Wandel 1999). New data show that this difference was mainly due to overestimated black hole masses in quiescent galaxies and bulge magnitudes in 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 (Seyfert 1s + quasars) and 35 quiescent galaxies. We find that broad line AGNs have an average black hole/bulge mass fraction of ∼ 0.0015 with a spread of 2-3, and a strong correlation (MBH ∝ L0.9±0.16 bulge ), consistent with the BH-bulge relation found in quiescent galaxies. This BH-bulge mass correlation for broad-line AGNs and quiescent galaxies is as good as the MBH-bulge velocity dispersion correlation reported for quiescent galaxies. We show that narrow line AGNs appear to have genuinely lower BH/bulge ratios MBH/Mbulge ∼ 10−4 − 10−3 and examine various explanations for the low BH/bulge ratio of narrow line AGNs. We find the black hole/bulge ratio in AGNs is inversly correlated with the emission-line width, which implies a strong linear relation between the broad emission line region and the host bulge luminosity. Finally, combining AGNs with observed and estimated stellar velocity dispersion we find a significant correlation (MBH ∝ σ3.5−5), consistent with that of quiescent galaxies. Subject headings: black hole physics, galaxies:bulges, galaxies:nuclei, galaxies:active, galaxies: Seyfert, quasars:general