RELATIVISTIC REDSHIFTS IN QUASAR BROAD LINES

Scott Tremaine, Yue Shen, Xin Liu, Abraham Loeb
2014 Astrophysical Journal  
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
more » ... pproximately 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.
doi:10.1088/0004-637x/794/1/49 fatcat:myr2g23gi5hczo2ssqvdqzmcru