MISCLASSIFIED TYPE 1 AGNS IN THE LOCAL UNIVERSE

Abstract

We search for misclassified type 1 AGNs among type 2 AGNs identified with emission line flux ratios, and investigate the properties of the sample. Using 4 113 local type 2 AGNs at 0.02 < z < 0.05 selected from Sloan Digital Sky Survey Data Release 7, we detected a broad component of the <TEX>$H{\alpha}$</TEX> line with a Full-Width at Half-Maximum (FWHM) ranging from 1 700 to <TEX>$19090km\;s^{-1}$</TEX> for 142 objects, based on the spectral decomposition and visual inspection. The fraction of the misclassified type 1 AGNs among type 2 AGN sample is ~3.5%, implying that a large number of missing type 1 AGN population may exist. The misclassified type 1 AGNs have relatively low luminosity with a mean broad <TEX>$H{\alpha}$</TEX> luminosity, log <TEX>$L_{H\alpha}=40.50{\pm}0.35\;erg\;s^{-1}$</TEX>, while black hole mass of the sample is comparable to that of the local black hole population, with a mean black hole mass, log <TEX>$M_{BH}=6.94{\pm}0.51\;M_{\odot}$</TEX>. The mean Eddington ratio of the sample is log <TEX>$L_{bol}/L_{Edd}=-2.00{\pm}0.40$</TEX>, indicating that black hole activity is relatively weak, hence, AGN continuum is too weak to change the host galaxy color. We find that the O III lines show significant velocity offsets, presumably due to outflows in the narrow-line region, while the velocity offset of the narrow component of the <TEX>$H{\alpha}$</TEX> line is not prominent, consistent with the ionized gas kinematics of general type 1 AGN population.