QSO Narrow [O III] Line Width and Host Galaxy Luminosity

Galaxy bulge luminosity L, black hole mass MBH, and stellar velocity dispersion σ* increase together in a way suggesting a close evolutionary relationship. Measurements of the MBH-σ* relationship as a function of cosmic time may shed light on the origin of this relationship. Direct measurements of σ* at high redshift are difficult, and the width of the narrow emission lines of active galactic nuclei (AGN) has been proposed as a surrogate for σ*. We investigate the utility of using σ[OIII] for σ* by examining host galaxy magnitudes and [O III] line widths for low-redshift QSOs. For radio-quiet QSOs, σ[OIII] is consistent in the mean with the value of σ* predicted by the Faber-Jackson relation. For our limited range of Lhost, scatter obscures the expected increase of σ[OIII] with Lhost. However, for a sample of AGN covering a wide range of measured or inferred σ*, there is a clear increase of σ[OIII] with σ*. Radio-loud QSOs on average have σ[OIII] smaller by 0.1 dex than radio-quiet QSOs of similar Lhost, at least for luminosities typical of PG QSOs. Star formation rates in our low-redshift QSOs are smaller than required in order to maintain the typical observed ratio of bulge mass to black hole mass.