Stellar Velocity Dispersion Measurements in High-Luminosity Quasar Hosts and Implications for the AGN Black Hole Mass Scale

TL;DR

This study measures stellar velocity dispersions in luminous quasars to examine their black hole mass relations, finding consistency with lower-luminosity AGNs and refining the virial factor for black hole mass estimates.

Contribution

It provides new stellar velocity dispersion data for high-luminosity quasars and recalculates the virial factor, improving the black hole mass scale calibration.

Findings

High-luminosity quasars follow the MBH-sigma relation.

Updated virial factor <f> = 4.31 +/- 1.05.

No correlation between luminosity and deviations from the MBH-sigma relation.

Abstract

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.