On the Systematic Bias in the Estimation of Black Hole Masses in Active Galactic Nuclei

Abstract

In this report, we find the \mbh estimated from the formalism of Wang et al. (2009)[1] are more consistent with those from the \mbh-$\sigma_*$ relation than those from previous single-epoch mass estimators, using a large sample of AGNs. Furthermore, we examine the differences between the line widths of \hb and \mgii in detail by comparing their line profiles. The flux around the line core and that in the wing of both \hb and \mgii show an opposite variation tendency, which indicates the BLR is multi-componential. The contribution of the wing makes the FWHM deviate from $\sigma_{line}$, and thus bias the \mbh estimated from previous single-epoch mass estimators. Thus the correction on the formalism suggested by Wang et al. (2009)[1] is crucial to \mbh estimation.