The second moment of the H$beta$ emission line is calculated for 329 narrow line Seyfert 1 galaxies (NLS1s) selected from the Sloan Digital Sky Survey (SDSS), which is used to calculate the central supermassive black hole (SMBHs) mass of each. We fin
d that the second moment depends strongly on the broader component of the H$beta$ line profile. We find that for the NLS1s requiring two Gaussians to fit the H$beta$ line the mean value of the SMBH mass from the H$beta$ second moment is larger by about 0.50 dex than that from the full width at half maximum (FWHM). Using the gas velocity dispersion of the core/narrow component of oiii $lambda$ 5007 to estimate the stellar velocity dispersion, $sigma_{*}$, the new mass makes NLS1s fall very close to the $mbh - sigma_{*}$ relation for normal AGNs. By using $sigma_{*}$ measured directly from SDSS spectra with a simple stellar population synthesis method, we find that for NLS1s with mass lower than $10^7 msun$, they fall only marginally below the $mbh - sigma_{*}$ relation considering the large scatter in the mass calculation.
Type II AGNs with polarimetric broad emission line provided strong evidence for the orientation-based unified model for AGNs. We want to investigate whether the polarimetric broad emission line in type II AGNs can be used to calculate their central s
upermassive black hole (SMBH) masses, like that for type I AGNs. We collected 12 type II AGNs with polarimetric broad emission line width from the literatures, and calculated their central black hole masses from the polarimetric broad line width and the isotropic oiii luminosity. We also calculate the mass from stellar velocity dispersion, $sigma_*$, with the $mbh-sigma_*$ relation.We find that: (1) the black hole masses derived from the polarimetric broad line width is averagely larger than that from the $mbh- sigma_*$ relation by about 0.6 dex, (2) If these type II AGNs follow $mbh-sigma_*$ relation, we find that the random velocity cant not be omitted and is comparable with the BLRs Keplerian velocity. It is consistent with the scenery of large outflow from the accretion disk suggested by Yong et al.
Using a large sample of 26623 quasars with redshifts in the range $1.5 le zle 5.1$ with civ $lambda$1549 AA emission line in Fifth Data Release of the Sloan Digital Sky Survey (SDSS), we investigate the cosmological evolution of the Baldwin Effect, i
.e. the relation between the equivalent width (EW) of the civ emission line and continuum luminosity. We confirm the earlier result that there exists a strong correlation between the civ EW and the continuum luminosity, and we find that, up to $zapprox 5$, the slope of the Baldwin Effect seems to have no effect of cosmological evolution. A sub-sample of 13960 quasars with broad civ $lambda$1549 AA emission line from SDSS is used to explore the origin of the Baldwin Effect. We find that civ EW have a strong correlation with the mass of supermassive black hole (SMBH), and a weak correlation with the Eddington ratio, $lb/ledd$. This suggests that the SMBH mass is probably the primary drive for the Baldwin Effect.
