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 (M_(BH)) and bulge luminosity (L_(bul)) in a sample of 45 massive, local (z approx< 0.35) type 1 active galactic nuclei (AGNs). We derive M_(BH) from published optical spectra assuming a spherical broad-line region, and L_(bul) from detailed two-dimensional decomposition of archival optical Hubble Space Telescope images. AGNs follow the M_(BH)-L_(bul) relation of inactive galaxies, but the zero point is shifted by an average of Δ log M_(BH) ≈ -0.3 dex. We show that the magnitude of the zero point offset, which is responsible for the intrinsic scatter in the M_(BH)-L_(bul) 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 M_(BH). The zero point offset can be explained by a change in the normalization of the virial product used to estimate M_(BH), 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.