RXTE AND BeppoSAX OBSERVATIONS OF MCG -5-23-16: REFLECTION FROM DISTANT COLD MATERIAL

摘要

We examine the spectral variability of the Seyfert 1.9 galaxy MCG -5-23-16 by using the Rossi X-Ray Timing Explorer (RXTE) and BeppoSAX observations spanning 2 years from 1996 April to 1998 April. During the first year the X-ray source brightens by a factor of ～25% on timescales of days to months. During this time, the reprocessed continuum emission seen with RXTE does not respond measurably to the continuum increase. However, by the end of the second year during the BeppoSAX epoch the X-ray source has faded again. This time, the reprocessed emission has also faded, indicating that the reprocessed flux has responded to the continuum. If these effects are caused by time delays due to the distance between the X-ray source and the reprocessing region, we derive a light crossing time between ～1 It-day and ～1.5 lt-yr. This corresponds to a distance of 0.001 to 0.55 pc, which implies that the reprocessed emission originates between 3 x 10~(15) and 1.6 x 10~(18) cm from the X-ray source. In other words, the reprocessing in MCG -5-23-16 is not dominated by the inner regions of a standard accretion disk.