Dynamical Mass of Type 2 Seyfert Nuclei

Abstract

We have derived the masses of central objects ($M_{BH}$) of nine type 2 Seyfert nuclei using the observational properties of the hidden broad H$\beta$ emission. We obtain the average dynamical mass, log$(M_{BH} / M_\odot) \simeq 8.00 \pm 0.51 - 0.475 log (\tau_{es}/1)$ where $\tau_{es}$ is the optical depth for electron scattering. If $\tau_{es} \sim 1$, this average mass is almost comparable with those of type 1 Seyfert nuclei. However, if $\tau_{es} \ll 1$, as is usually considered, the average mass of type 2 Seyfert nuclei may be more massive than that of type 1s. We discuss implications for issues concerning both the current unified model of Seyfert nuclei and physical conditions of the electron scattering regions.