Black Hole Growth & the M_BH--Bulge Relations

Abstract

We present the black hole mass--bulge velocity dispersion relation for a complete sample of 75 soft X-ray selected AGNs. We find that the AGNs with highest accretion rates relative to Eddington lie below the \mbh--\sig\ relation of broad line Seyfert 1s, confirming the Mathur et al (2001) result. The statistical result is robust and not due to any systematic measurement error. This has important consequences towards our understanding of black hole formation and growth: black holes grow by accretion in well formed bulges. As they grow, they get closer to the \mbh--\sig relation for normal galaxies. The accretion is highest in the beginning and dwindles as time goes by. Our result does not support theories of the \mbh--\sig relation in which the black hole mass is a constant fraction of the bulge mass/ velocity dispersion {\it at all times} or those in which bulge growth is controlled by AGN feedback.