Supermassive Black Holes in Active Galactic Nuclei. II. Calibration of   the M-sigma Relationship for AGNs
  We calibrate reverberation-based black hole masses in active galactic nuclei (AGNs) by using the correlation between black hole mass, M, and bulge/spheroid stellar velocity dispersion, sigma. We use new measurements of sigma for 6 AGNs and published velocity dispersions for 10 others, in conjunction with improved reverberation mapping results, to determine the scaling factor required to bring reverberation-based black hole masses into agreement with the quiescent galaxy M-sigma relationship. The scatter in the AGN black hole masses is found to be less than a factor of 3. The current observational uncertainties preclude use of the scaling factor to discriminate between broad-line region models. 
Christopher A. Onken (1), Laura Ferrarese (2), David Merritt (3),   Bradley M. Peterson (1), Richard W. Pogge (1), Marianne ...