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arXiv · 1406.2468

Relativistic redshifts in quasar broad lines

Scott Tremaine·Yue Shen·Xin Liu·Abraham Loeb
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Abstract

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.

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Scott Tremaine, Yue Shen, Xin Liu, Abraham Loeb. 2014-06-10. Relativistic redshifts in quasar broad lines. https://doi.org/10.1088/0004-637x/794/1/49

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