Chandra and Xmm-newton Observations of the Nucleus of Centaurus A

We present X-ray spectra of the nucleus of the nearby radio galaxy Centaurus A from observations with the XMM-Newton EPIC CCD cameras (two exposures separated by 12 months) and the Chandra High Energy Transmission Grating Spectrometer (HETGS). For the first time in an FRI galaxy, we resolve fluorescent Kα emission from cold, neutral, or near-neutral iron at 6.4 keV, with an r.m.s. line width of ∼ 20 eV. The Fe line parameters observed are consistent with fluorescent emission from material at a large distance from the AGN, either in the form of an absorber that nearly completely surrounds the central engine, or a torus that lies predominantly out of the line of sight. Unresolved emission lines from neutral Si Kα at 1.74 keV and neutral S Kα at 2.30 keV are also detected. We find no evidence in the data for a previously reported 6.8 keV broadened Fe line. The continuum spectrum is well-fitted with a combination of a heavily absorbed power-law component that we relate, using Bondi theory, to accretion phenomena in the form of a standard, geometrically thin, optically thick disk, and a second, less absorbed, power-law component that we associate with emission from the sub-parsec VLBI radio jet. Subject headings: galaxies: active galaxies: individual (Centaurus A, NGC 5128) galaxies: jets X-rays: galaxies