Stellar and gaseous velocity dispersions in type II AGNs at 0.3 < z < 0.83 from the Sloan Digital Sky Survey

We apply the stellar population synthesis code by Cid Fernandes 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 (sigma(*)) are obtained for 33 type II AGNs with significant stellar absorption features. According to the L-[O III] criterion of 3 x 10(8) L-circle dot, 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 (sigma(c)(*)). We also calculate the supermassive black hole masses from sigma(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]lambda lambda 4959, 5007 and [O II]lambda lambda 3727, 3729) in these 33 stellar-light-subtracted spectra. We also measure the gas velocity dispersion (sigma(g)) from these multiple transitions, and find that the relation between sigma(g) and sigma(c)(*) becomes much weaker at higher redshifts than in smaller redshifts. The distribution of <sigma(g)/sigma(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 sigma(g) of the core [O III] and [O II] lines can trace sigma(c)(*) within about 0.1 dex in the logarithm of sigma(c)(*). For the secondary driver, we find that the deviation of sigma(g) from sigma(c)(*) is correlated with the Eddington ratio.