Special relativistic effects on the strength of the fluorescent K iron line from black hole accretion disks.

C. S. Reynolds and A. C. Fabian
JILA, University of Colorado, Boulder, Colorado, CO 80309-0440, USA
Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA

Abstract:

The broad iron K emission line, commonly seen in the X-ray spectrum of Seyfert nuclei, is thought to originate when the inner accretion disk is illuminated by an active disk-corona. We show that relative motion between the disk and the X-ray emitting material can have an important influence on the observed equivalent width (EW) of this line via special relativistic aberration and Doppler effects. We suggest this may be relevant to understanding why the observed EW often exceeds the prediction of the standard X-ray reflection model. Several observational tests are suggested that could disentangle these special relativistic effects from iron abundance effects.

• Introduction
• A stationary slab illuminated by a moving source
  • Influence of the motion on the absolute line photon emission rate
  • Differential beaming and the equivalent width of the line
• Discussion and conclusions
• References
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