Virilization of the Broad Line Region in Active Galactic Nuclei - connection between shifts and widths of broad emission lines

TL;DR

This study examines the virilization of Hbeta and Mg II emission lines in 287 AGN, revealing their potential as black hole mass estimators and exploring the relationship between line shifts and widths.

Contribution

It demonstrates that Hbeta is a reliable virial estimator and clarifies the limitations of Mg II line widths and shifts for mass estimation.

Findings

Hbeta line is a good virial estimator of black hole mass

Intrinsic redshift of Hbeta is mainly gravitational

Mg II line wings are not suitable for virial mass estimation

Abstract

We investigate the virilization of the emission lines Hbeta and Mg II in the sample of 287 Type 1 Active Galactic Nuclei taken from the Sloan Digital Sky Survey database. We explore the connections between the intrinsic line shifts and full widths at different levels of maximal intensity. We found that: (i) Hbeta seems to be a good virial estimator of black hole masses, and an intrinsic redshift of Hbeta is dominantly caused by the gravitational effect, (ii) there is an anti-correlation between the redshift and width of the wings of the Mg II line, (iii) the broad Mg II line can be used as virial estimator only at 50% of the maximal intensity, while the widths and intrinsic shifts of the line wings can not be used for this purpose.