Observation of Centaurus A by theRossi X‐Ray Timing Explorer

The Rossi X-Ray Timing Explorer made a short (10 ks) observation of the radio galaxy Centaurus A on 1996 August 14. Analysis of the combined 2.5-240 keV spectrum has revealed a heavily absorbed (N(H) = 9.42 +/- 0.24 x 10(22) cm(-2)) primary power law (Gamma = 1.86 +/- 0.015) and an iron line due to fluorescence of cold matter (EW = 162 +/- 25 eV). Flux from a jet, a primary flux scattered into the line of sight, or a primary flux seen through a partial absorber was not required. The iron-line width is unresolved at the 95% confidence level (sigma < 0.54 keV). No significant variability in the iron-line flux is seen from measurements over the last two decades, while the overall continuum flux varied by more than a factor of 4, which implies that the line emission region is distant from that of the primary emission. While radio-quiet Seyfert galaxies exhibit spectral components attributable to Compton reflection from cold matter, Cen A reveals no such component (exposed solid angle ratio Omega/2 pi: less than or equal to 0.09). This supports unified models of active galaxies that have little difference between Seyfert 2 and low-luminosity radio galaxies.