What Causes the Scatter in the Black Hole Mass vs. Velocity Dispersion Relation for AGNs?
This dataset allows us to reproduce the black hole mass vs. velocity dispersion relation, using the H\beta width and optical luminosity to derive the black hole mass, and using the [O III] \lambda5007 width as a surrogate for the stellar velocity dispersion. While the fit to this relationship is quite similar to that for non-active galaxies, there is a large scatter, exceeding observational errors. An analysis of this scatter in terms of the measured emission lines shows that the QSOs that have [O III] too wide for their calculated black hole mass tend to have higher luminosity, narrower H\beta, and come from the strong Fe II/weak [O III] end of the E1 sequence. Possible explanations of this include simple models in which some of the characteristics are determined by orientation.
