2002A&A...395..465B

We assume that the gravitational instability of standard thin accretion disks leads to the Broad Line Regions (BLRs), the B band luminosity comes from standard thin disk and the motion of BLRs is virial. The central black hole masses, the accretion rates and the disk inclinations to the line of sight for 17 Seyfert 1 galaxies and 17 Palomar-Green (PG) quasars have been calculated. Our results are sensitive to the α parameter of the standard α disk. With the same values of α (α=1), calculated central black hole masses for 17 Seyfert 1 galaxies are consistent with those from Kaspi et al. (2000ApJ...533..631K) while those for 17 PG quasars are larger than those from Kaspi et al. (2000ApJ...533..631K) by almost 2 orders of magnitude. Inclinations of 17 Seyfert 1 galaxies are about 6 times larger than those of 17 PG quasars. These inclinations, with a mean value of 32° for 17 Seyfert 1 galaxies that agrees well with the result obtained by fitting the iron Kα lines of Seyfert 1 galaxies observed with ASCA (Nandra et al., 1997ApJ...477..602N) and the result obtained by Wu & Han (2001ApJ...561L..59W) further support for the orientation-dependent unification scheme of active galactic nuclei. There is a relation between the FWHM of Hβ and the inclination, namely the inclination is smaller in AGNs with smaller FWHM of Hβ. The effect of inclinations in narrow line Seyfert 1 galaxies (NLS1s) should be considered when one studies the physics of NLS1s. The need for higher value of α for PG quasars maybe shows that our model is not suitable for PG quasars if we think inclinations of PG quasars are in the inclination levels of Seyfert 1 galaxies. With our model, we also show that the size of BLRs relates not only to the luminosity, but also to the accretion rates. More knowledge of BLR dynamics, accretion disks and optical luminosity are needed to improve the determination of black hole masses, accretion rates and inclinations in AGNs.