SDSS spectroscopy for blazars in the $Fermi$ LAT bright AGN sample
  We have collected all available spectra and photometric data from SDSS
catalogue for bright AGNs complied from the first three months of the Fermi
large area telescope all-sky survey. Based on the 106 high-confidence and 11
low-confidence association bright AGN list, the photometry data are collected
from SDSS DR7 for 28 sources (12 BL Lacs and 16 FSRQs), two of which are
low-confidence association bright AGNs. Among these 28 SDSS photometric
sources, SDSS spectra are available for 20 sources (6 BL Lacs and 14 FSRQs).
The black hole mass M_BH and the broad line region (BLR) luminosity were
obtained for 14 FSRQs by measuring the line-width and strength of broad
emission lines from SDSS spectra. The broad emission lines measurements of five
FSRQs are presented for the first time in this work. The optical continuum
emission of these 14 FSRQs is found to be likely dominated by the nonthermal
jet emission through comparing the relationship between the broad Mg II line
and continuum luminosity to that of radio quiet AGNs. The black hole mass of 14
FSRQs ranges from 10^8.2 to 10^9.9 solar mass, with most of sources larger than
10^9 solar mass. The Eddington ratio L_bol/L_Edd ranges from 10^-1.5 to ~ 1.
This implies that the optically thin, geometrically thick accretion disk may
exist in these FSRQs.
