The Suzaku observation of the nucleus of the radio-loud active galaxy centaurus a: Constraints on abundances of the accreting material

A. Markowitz*, T. Takahashi, S. Watanabe, K. Nakazawa, Y. Fukazawa, M. Kokubun, K. Makishima, H. Awaki, A. Bamba, N. Isobe, J. Kataoka, G. Madejski, R. Mushotzky, T. Okajima, A. Ptak, J. N. Reeves, Y. Ueda, T. Yamasaki, T. Yaqoob

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)


A Suzaku observation of the nucleus of the radio-loud AGN Centaurus A in 2005 has yielded a broadband spectrum spanning 0.3-250 keV. The net exposure times after screening were 70 ks per X-ray Imaging Spectrometer (XIS) camera, 60.8 ks for the Hard X-ray Detector ( HXD) PIN, and 17.1 ks for the HXD GSO. The hard X-rays are fit by two power laws of the same slope, absorbed by columns of 1.5 and 7 × 1023 cm-2, respectively. The spectrum is consistent with previous suggestions that the power-law components are X-ray emission from the subparsec VLBI jet and from Bondi accretion at the core, but it is also 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 VAPEC model, plus a third power-law component to account for scattered nuclear emission, 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 Fe Ka line width yields a 200 It-day lower limit on the distance from the black hole to the line-emitting gas. Fe, Ca, and S K-shell absorption edges are detected. Elemental abundances are constrained via absorption edge depths and strengths of the fluorescent and diffuse plasma emission lines. The high metallicity ([Fe/H] = +0.1) of the circumnuclear material suggests that it could not have originated in the relatively metal-poor outer halo unless enrichment by local star formation has occurred. Relative abundances are consistent with enrichment from Type II and Ia supernovae. 2007. The American Astronomical Society. All rights reserved.

Original languageEnglish
Pages (from-to)209-224
Number of pages16
JournalAstrophysical Journal
Issue number1 PART 1
Publication statusPublished - 2007 Aug 10
Externally publishedYes


  • Galaxies: active
  • Galaxies: individual (NGC 5128)
  • X-rays: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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