Virial Black Hole Mass Estimates for 280,000 AGNs from the SDSS
  Broad-Band Photometry and Single Epoch Spectra
  We use the Sloan Digital Sky Survey (SDSS) Quasar Data Release 12 (DR12Q),
containing nearly 300,000 AGNs, to calculate the monochromatic luminosities at
5100\AA, 3000\AA, and 1350\AA, derived from the broad-band extinction-corrected
SDSS magnitudes. After matching them to their counterparts based on spectra and
published in the SDSS Quasar Data Release 7 (DR7Q), we find perfect
correlations with minute mean offsets ($\sim$0.01 dex) and dispersions of
differences of 0.11, 0.10, 0.12 dex, respectively, across a 2.5 dex luminosity
range. We then estimate the active galactic nuclei (AGNs) black hole masses
using the broad line region radius--luminosity relations and the FWHM of the
MgII and CIV emission lines, to provide a catalog of 283,032 virial black hole
mass estimates (132,451 for MgII, 213,068 for CIV, and 62,487 for both) along
with the bolometric luminosity and the Eddington ratio estimates for
$0.1<z<5.5$ and for roughly a quarter of the sky covered by SDSS. The black
hole mass estimates from MgII turned out to be closely matched to the ones from
DR7Q with the dispersion of differences of 0.34 dex across a $\sim$2 dex BH
mass range. We uncovered a bias in the derived CIV FWHMs from DR12Q as compared
to DR7Q, that we correct empirically. The CIV BH mass estimates should be used
with caution because the CIV line is known to cause problems in the BH mass
estimation from single-epoch spectra. Finally, after the FWHM correction, the
AGN black hole mass estimates from CIV closely match the DR7Q ones (with the
dispersion of 0.28 dex), and more importantly the MgII and CIV BH masses agree
internally with the mean offset of 0.07 dex and the dispersion of 0.39 dex.
