The canonical X-ray/gamma-ray spectrum of Seyfert Is and low-state Galactic black hole candidates

A. A. Zdziarski, M. Gierlinski, D. Gondek, P. Magdziarz

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27 Citations (Scopus)


We review broad-band X-ray/γ-ray spectra of radio-quiet Seyfert Is as well as of Galactic black hole candidates in the low state. The spectra share their basic components: an underlying power law, a Compton-reflection component with an Fe Ka line, low-energy absorption by cold matter, and a high-energy cutoff above ∼ 200 keV. The X-ray energy spectral index, a, is in the range ∼ 0.8-1 in the average Seyfert-1 spectra from Ginga, EXOSAT and OSSE and in the available X-ray/7-ray spectra of bright Seyfert Is. The low-state spectra of Cyg X-l and GX 339-4 from simultaneous Ginja/OSSE observations have a c± 0.6-0.8. The Comptonreflection component corresponds to cold matter (e.g., inner or outer parts of an accretion disk) covering a solid angle of ∼ (0.4-0.8) x 2îT as seen from the X-ray source. Cutoffs in soft 7-rays correspond to the plasma temperature of order of 100 keV. The intrinsic spectra are well explained by thermal Comptonization in plasmas with the Thomson optical depth of r ∼ 1.

Original languageEnglish
Pages (from-to)553-558
Number of pages6
JournalAstronomy and Astrophysics Supplement Series
Issue number4
Publication statusPublished - 1 Dec 1996


  • Galaxies: Seyfert
  • Gammarays: Observations
  • Radiation mechanisms: Thermal
  • Stars: Individual: Cyg x-1
  • X-rays: Galaxies

ASJC Scopus subject areas

  • General Physics and Astronomy


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