Chandra and XMM-Newton Observations of the Nucleus of Centaurus APublication date: 10 Sep 2004 Authors: Evans, D. A., et al.
Journal: ApJ Copyright: IOP Publishing 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 HETGS. For the first time in an FR I type galaxy, we resolve fluorescent K alpha emission from cold, neutral, or near-neutral iron at 6.4 keV, with an rms line width of ~20 eV. The Fe line parameters observed are consistent with fluorescent emission from material at a large distance from the active galactic nucleus, 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 K alpha at 1.74 keV and neutral S K alpha 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 subparsec VLBI radio jet.
Last Update: 04 Apr 2012
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