MISCLASSIFIED TYPE 1 AGNS IN THE LOCAL UNIVERSE

• Published in: Journal of the Korean astronomical society Vol. 47; no. 5; pp. 167 - 178
• Main Authors: Woo, Jong-Hak, Kim, Ji-Gang, Park, Daeseong, Bae, Hyun-Jin, Kim, Jae-Hyuk, Lee, Seung-Eon, Kim, Sang Chul, Kwon, Hong-Jin
• Format: Journal Article
• Language: Korean
• Published: 2014
• Subjects: galaxies: active; galaxies: Seyfert: $H{\alpha}$ emission line; galaxies: nuclei
• ISSN: 1225-4614; 2288-890X

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 $H{\alpha}$ line with a Full-Width at Half-Maximum (FWHM) ranging from 1 700 to $19090km\;s^{-1}$ 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 $H{\alpha}$ luminosity, log $L_{H\alpha}=40.50{\pm}0.35\;erg\;s^{-1}$, while black hole mass of the sample is comparable to that of the local black hole population, with a mean black hole mass, log $M_{BH}=6.94{\pm}0.51\;M_{\odot}$. The mean Eddington ratio of the sample is log $L_{bol}/L_{Edd}=-2.00{\pm}0.40$, 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 $H{\alpha}$ line is not prominent, consistent with the ionized gas kinematics of general type 1 AGN population.