SIMBAD references

The ratio in number between unobscured (type 1) and obscured (type 2) active galactic nuclei (AGNs) is often used to explore the structure of the torus in the unified scheme for AGNs. Oh et al. (2015) investigated the type 1 AGN fraction on two-dimensional space in terms of black hole mass (M_BH) and bolometric luminosity (L_bol) and found that the fraction changes depending on both M_BH and L_bol, forming a ridge-shaped distribution. In this study, based on the up-to-date type 1 AGN catalog of Oh et al. (2015), we examine how the trend of the type 1 AGN fraction in the M_BH-L_bol plane is affected by the different methods used to derive M_BH and L_bol, and suggest an analytic model to explain the observations. We use galaxies from the Sloan Digital Sky Survey Data Release 7 in the redshift range 0.01 z 0.2. In estimating L_bol, we employ two different methods using [O III] and/or [O I] emission lines, and find that the L_bol values obtained from the two methods agree well. We consider the M_BH–σ_* relation, the M_BH-L_bulge relation, and the single-epoch Hα-based M_BH estimate in calculating M_BH. We find that the trends of the type 1 AGN fraction with respect to M_BH and L_bol are similar for the different methods of deriving L_bol but different when using different methods to derive M_BH. We present a model based on the clumpy-torus scheme that reproduces the ridge-shaped distribution of the fraction parallel to the iso-Eddington ratio lines.