Stellar and gaseous velocity dispersions in type II AGNs at 0.3

We apply the stellar population synthesis code by Cid Femandes et al. to model the stellar contribution for a sample of 209 type II active galactic nuclei (AGNs) at 0.3 < z < 0.83 from the Sloan Digital Sky Survey. The reliable stellar velocity dispersions (σ*) are obtained for 33 type II AGNs with significant stellar absorption features. According to the L [OIII] criterion of 3 x 10 8 L ⊙ , 20 of which can be classified as type II quasars. We use the formula of Greene and . Ho to obtain the corrected stellar velocity dispersions (σ c *). We also calculate the supermassive black hole masses from σ c * in these high-redshift type II AGNs. The [O III] luminosity is correlated with the black hole mass (although no correlation between the extinction-corrected [O III] luminosity and the black hole mass), and no correlation is found between the Eddington ratio and the [O III] luminosity or the corrected [O III] luminosity. Three sets of two-component profiles are used to fit multiple emission transitions ([O III]λλ4959, 5007 and [O II]λλ3727, 3729) in these 33 stellar-light-subtracted spectra. We also measure the gas velocity dispersion (σ g ) from these multiple transitions, and find that the relation between σ g and σ c * becomes much weaker at higher redshifts than in smaller redshifts. The distribution of (σ g /σ c *) is 1.24 ± 0.76 for the core [O III] line and 1.20 ± 0.96 for the [O II] line, which suggests that σ g of the core [O III] and [O II] lines can trace σ c * within about 0.1 dex in the logarithm of σ c *. For the secondary driver, we find that the deviation of σ g from σ c * is correlated with the Eddington ratio.