2018ApJ...859..116K

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-σ_* relation and bolometric corrections scaled from the extinction-corrected [O III] λ5007 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] λλ3726, 3729, [S II] λλ6716, 6731, and [O III] λ5007, 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 ≃ 10^6.5 to 10^10.4 M_☉ (median 10^8.2 M_☉). Type 2 quasars have characteristically large Eddington ratios (L_bol/L_Edd ≃ 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.