Black Hole Mass Estimation in Type 1 AGN: H${\hat{I}}^2$ vs. Mg II lines and the role of Balmer continuum

Abstract

Here we investigate the H${\hat{I}}^2$ and Mg II spectral line parameters used for the black hole mass (M${}_{\mathrm{BH}}$) estimation for a sample of Type 1 Active Galactic Nuclei (AGN) spectra selected from the Sloan Digital Sky Survey (SDSS) database. We have analyzed and compared the virialization of the H${\hat{I}}^2$ and Mg II emission lines, and found that the H${\hat{I}}^2$ line is more confident virial estimator than Mg II. We have investigated the influence of the Balmer continuum emission to the M${}_{\mathrm{BH}}$ estimation from the UV parameters, and found that the Balmer continuum emission can contribute to the overestimation of the M${}_{\mathrm{BH}}$ on average for ~ 5% (up to 10%).

9 pages, 3 figures, Accepted for publication in Frontiers in Astronomy and Space Sciences