Detecting Compton reflection and a broad iron line in MCG -5-23-16 with RXTE

We report the detection with the Rossi X-Ray Timing Explorer (RXTE) of a Compton reflection signature in the Seyfert galaxy MCG -5-23-16. RXTE also resolves the Fe K alpha fluorescence line with FWHM similar to 48,000 km s(-1). This measurement provides the first independent confirmation of ASCA detections in Seyfert galaxies of broad Fe K alpha lines that are thought to be the signature of emission from the inner regions of an accretion disk orbiting a black hole. Under the assumption that reflection arises from an isotropic source located above a neutral accretion disk, and using a theoretical model that accounts for the dependence of the reflected spectrum on inclination angle, we derive a 90% confidence range for the disk inclination of i = 50 degrees-81 degrees. The large inclination is consistent with that expected from the unified model for MCG -5-23-16 based on its Seyfert 1.9 classification. If we assume that the high-energy cutoff in the incident spectrum lies at energies larger than a few hundred keV, then the equivalent width of the Fe K alpha line is much larger than predicted for the amount of reflection. This implies either an enhanced iron abundance, a covering factor of reflecting material c(f) > 0.5, or a cutoff in the incident spectrum at energies between similar to 60 and similar to 200 keV.