Stellar Velocity Dispersion Measurements in High-Luminosity Quasar Hosts
  and Implications for the AGN Black Hole Mass Scale
  We present new stellar velocity dispersion measurements for four luminous
quasars with the NIFS instrument and the ALTAIR laser guide star adaptive
optics system on the Gemini North 8-m telescope. Stellar velocity dispersion
measurements and measurements of the supermassive black hole masses in luminous
quasars are necessary to investigate the coevolution of black holes and
galaxies, trace the details of accretion, and probe the nature of feedback. We
find that higher-luminosity quasars with higher-mass black holes are not offset
with respect to the MBH-sigma relation exhibited by lower-luminosity AGNs with
lower-mass black holes, nor do we see correlations with galaxy morphology. As
part of this analysis, we have recalculated the virial products for the entire
sample of reverberation-mapped AGNs and used these data to redetermine the mean
virial factor hfi that places the reverberation data on the quiescent
M_BH-sigma relation. With our updated measurements and new additions to the AGN
sample, we obtain <f> = 4.31 +/- 1.05, which is slightly lower than, but
consistent with, most previous determinations.
