Disks Irradiated by Beamed Radiation from Compact Objects

We examine the reprocessing of X-ray radiation from compact objects byaccretion disks when the X-ray emission from the star is highly beamed. Thereprocessed flux for various degrees of beaming and inclinations of the beamaxis with respect to the disk is determined. We find that, in the case wherethe beam is produced by a non-relativistic object, the intensity of the emittedspectrum is highly suppressed if the beam is pointing away from the disk.However, for beams produced by compact objects, general relativistic effectscause only a small reduction in the reradiated flux even for very narrow beamsoriented perpendicularly to the disk. This is especially relevant inconstraining models for the anomalous X-ray pulsars, whose X-ray emission ishighly beamed. We further discuss other factors that can influence the emissionfrom disks around neutron stars.Comment: 11 pages with 4 figures, accepted to ApJ Letter