The Suzaku Observation of the Nucleus of the Radio Loud Active Galaxy Centaurus A(Chapter 10. Super Massive Black Holes, The Extreme Universe in the Suzaku Era)

概要

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A Suzaku observation of the nucleus of the radio-loud AGN Centaurus A in 2005 has yielded a broadband spectrum spanning 0.3 to 250keV. The hard X-rays are fit by two power laws, absorbed by columns of 1.5 and 7×10^<23> cm^<-2> respectively. The spectrum consistent with previous suggestions that the power-law components are X-ray emission from the sub-pc VLBI jet and from Bondi accretion at the core, or are consistent with a partial covering interpretation. The soft band is dominated by thermal emission from the diffuse plasma and is fit well by a two-temperature collisional ionization emission model, plus a third power-law component to account for scattered nuclear emission, kpc-scale jet emission, and emission from X-ray Binaries and other point sources. Narrow fluorescent emission lines from Fe, Si, S, Ar, Ca and Ni are detected. The width of the Fe Kα line yields a 200 light-day lower limit on the distance from the black hole to the line-emitting gas. K-shell absorption edges due to Fe, Ca, and S are detected. The high metallicity ([Fe/H]=+0.1) of the circumnuclear material suggests that the accreting material could not have originated in the metal-poor outer halo unless enrichment by local star formation has occurred. Relative element abundances are consistent with enrichment due to local star formation processes.
2007-12-19