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A two-temperature accretion disk model for Cygnus X-1 - Structure and spectrum
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1976
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The paper presents a model for Cygnus X‑1 involving an accretion disk around a black hole that explains the observed X‑ray spectrum from 8 to 500 keV. The authors construct a two‑temperature accretion disk in which the inner, optically thin, gas‑pressure dominated region is geometrically thick, has electron temperatures near 10^9 K and ion temperatures up to several hundred times higher, and produces the >8 keV spectrum through inverse Compton scattering of soft X‑rays, calculated by numerically integrating a modified Kompaneets equation that includes photon escape. Published in The Astrophysical Journal (Feb 1976), DOI 10.1086/154162, with full text available via ADS and SIMBAD.
view Abstract Citations (1043) References (24) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A two-temperature accretion disk model for Cygnus X-1: structure and spectrum. Shapiro, S. L. ; Lightman, A. P. ; Eardley, D. M. Abstract A model for Cygnus X-1, involving an accretion disk around a black hole, is presented which can explain the observed X-ray spectrum from 8 to 500 keV. In particular, a detailed model is constructed for the structure of an accretion disk whose inner region is considerably hotter and geometrically thicker than previous disk models. The inner region of the disk is optically thin to absorption, is gas-pressure dominated, and yields, from first principles, electron temperatures of 1 billion K and ion temperatures 3 to 300 times hotter. The spectrum above 8 keV is produced by inverse Compton scattering of soft X-ray photons in the two-temperature inner region of the disk. This spectrum is computed by numerical integration of the Kompane'ets equation, modified to account for escape of photons from a region of finite (order unity) electron-scattering optical depth. Publication: The Astrophysical Journal Pub Date: February 1976 DOI: 10.1086/154162 Bibcode: 1976ApJ...204..187S Keywords: Astronomical Models; Black Holes (Astronomy); Radiative Transfer; X Ray Sources; X Ray Stars; Compton Effect; Disks (Shapes); Electron Energy; Emission Spectra; Ion Temperature; X Ray Spectra; Astrophysics full text sources ADS | data products SIMBAD (1)