Relativistic redshifts in quasar broad lines
  The broad emission lines commonly seen in quasar spectra have velocity widths
of a few per cent of the speed of light, so special- and general-relativistic
effects have a significant influence on the line profile. We have determined
the redshift of the broad H-beta line in the quasar rest frame (determined from
the core component of the [OIII] line) for over 20,000 quasars from the Sloan
Digital Sky Survey DR7 quasar catalog. The mean redshift as a function of line
width is approximately consistent with the relativistic redshift that is
expected if the line originates in a randomly oriented Keplerian disk that is
obscured when the inclination of the disk to the line of sight exceeds ~30-45
degrees, consistent with simple AGN unification schemes. This result also
implies that the net line-of-sight inflow/outflow velocities in the broad-line
region are much less than the Keplerian velocity when averaged over a large
sample of quasars with a given line width.
