The Black Hole Masses and Eddington Ratios of Type 2 Quasars

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 (M-BH) and Eddington ratio (L-bol/L-Edd) for 669 type. 2 quasars selected from the Sloan Digital Sky Survey, using BH masses estimated from the M-BH-sigma(*) relation and bolometric corrections scaled from the extinction-corrected [O III] 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 [O II] lambda lambda 3726, 3729, [S II] lambda lambda 6716, 6731, and [O III] 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 M-BH approximate to 10(6.5) to 10(10.4)M circle dot (median 10(8.2)M circle dot). Type. 2 quasars have characteristically large Eddington ratios (L-bol/L-Edd approximate to 10(-2.9) -10(1.8); median 10(-0.7)), slightly higher than in type. 1 quasars of similar redshift; the luminosities of similar to 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.