The Origin of the Intrinsic Scatter in the Relation Between Black Hole Mass and Bulge Luminosity for Nearby Active Galaxies*

摘要

We investigate the origin of the intrinsic scatter in the correlation between black hole mass (MBH) and bulge luminosity (Lbul) in a sample of 45 massive, local (z 0.35) type 1 active galactic nuclei (AGNs). We derive MBH from published optical spectra assuming a spherical broad-line region, and Lbul from detailed two-dimensional decomposition of archival optical Hubble Space Telescope images. AGNs follow the MBH ? Lbul relation of inactive galaxies, but the zero point is shifted by an average of Δ log MBH ≈ ? 0.3 dex. We show that the magnitude of the zero point offset, which is responsible for the intrinsic scatter in the MBH ? Lbul relation, is correlated with several AGN and host galaxy properties, all of which are ultimately related to, or directly impact, the BH mass accretion rate. At a given bulge luminosity, sources with higher Eddington ratios have lower MBH. The zero point offset can be explained by a change in the normalization of the virial product used to estimate MBH, in conjunction with modest BH growth (~10%-40%) during the AGN phase. Galaxy mergers and tidal interactions appear to play an important role in regulating AGN fueling in low-redshift AGNs.