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Description
Type 2 quasars are an important constituent of active galaxies, possibly representing the evolutionary precursors of traditionally studied type 1 quasars. We characterize the black hole (BH) mass (MBH) and Eddington ratio (Lbol/LEdd) for 669 type 2 quasars selected from the Sloan Digital Sky Survey, using BH masses estimated from the MBH-{sigma}* relation and bolometric corrections scaled from the extinction-corrected [OIII]{lambda}5007 luminosity. When stellar velocity dispersions cannot be measured directly from the spectra, we estimate them from the core velocity dispersions of the narrow emission lines [OII]{lambda}{lambda}3726,3729, [SII]{lambda}{lambda}6716,6731, and [OIII]{lambda}5007, which are shown to trace the gravitational potential of the stars. Energy input from the active nucleus still imparts significant perturbations to the gas kinematics, especially to high-velocity, blueshifted wings. Nonvirial motions in the gas become most noticeable in systems with high Eddington ratios. The BH masses of our sample of type 2 quasars range from MBH~10^6.5^ to 10^10.4^M_{sun}_ (median 10^8.2^M_{sun}_). Type 2 quasars have characteristically large Eddington ratios (Lbol/LEdd~10^-2.9^-10^1.8^; median 10^-0.7^), slightly higher than in type 1 quasars of similar redshift; the luminosities of ~20% of the sample formally exceed the Eddington limit. The high Eddington ratios may be consistent with the notion that obscured quasars evolve into unobscured quasars.
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