The spectral properties of the AGN type 2 sample: The search for the sigma surrogate

Abstract

M B H - Σ* relation is the most commonly used method for the MBH (mass of the super-massive black hole) estimation in the AGNs (Active Galactic Nuclei) Type 2. Since σ* (stellar velocity dispersion) is in some cases diluted by the noise in AGN Type 2 spectra, it is of interest to find appropriate surrogate for σ* in some prominent AGN Type 2 spectral characteristics. Here we used the large sample of the AGN Type 2 spectra from SDSS and try to find under what circumstances the width of the [O III]5007 Å emission lines can be used as σ* surrogate. We find that only in the case of objects with no asymmetry in the narrow emission lines profiles, the width of the [O III] core can be used appropriately as σ* surrogate, since outflow kinematics do not affect significantly the [O III] profile.