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          Institute: MPI für Astrophysik     Collection: High Energy Astrophysics at MPA     Display Documents

ID: 10994.0, MPI für Astrophysik / High Energy Astrophysics at MPA
Resolving the composite Fe K alpha emission line in the Galactic black hole Cygnus X-1 with Chandra
Authors:Miller, J. M.; Fabian, A. C.; Wijnands, R.; Remillard, R. A.; Wojdowski, P.; Schulz, N. S.; Di Matteo, T.; Marshall, H. L.; Canizares, C. R.; Pooley, D.; Lewin, W. H. G.
Date of Publication (YYYY-MM-DD):2002
Title of Journal:The Astrophysical Journal
Journal Abbrev.:Astrophys. J.
Issue / Number:1
Start Page:348
End Page:356
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:We observed the Galactic black hole Cyg X-1 with the Chandra High Energy Transmission Grating Spectrometer for 30 ks on 2001 January 4. The source was in an intermediate state, with a flux that was approximately twice that commonly observed in its persistent low/hard state. Our best-fit model for the X-ray spectrum includes narrow Gaussian emission line (E = 6.415 +/- 0.007 keV, FWHM = 80(-19)(+28) eV, W = 16(-2)(+3) eV) and broad-line (E = 5.82(-0.07)(+0.06) keV, FWHM = 1.9(-0.3)(+0.5) keV, W = 140(-40)(+70) eV) components, and a smeared edge at 7.3 +/- 0.2 keV (tau similar to 1.0). The broad-line profile is not as strongly skewed as those observed in some Seyfert galaxies. We interpret these features in terms of an accretion disk with irradiation of the inner disk producing a broad Fe Kalpha emission line and edge, and irradiation of the outer disk producing a narrow Fe Kalpha emission line. The broad line is likely shaped predominantly by Doppler shifts and gravitational effects, and to a lesser degree by Compton scattering due to reflection. We discuss the underlying continuum X-ray spectrum and these line features in the context of diagnosing the accretion flow geometry in Cyg X-1 and other Galactic black holes.
Free Keywords:accretion; accretion disks; black hole physics; relativity; stars : individual (Cygnus X-1); X-rays : binaries; X-rays : individual (Cygnus X-1)
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astrophysik
External Affiliations:MIT, Ctr Space Res, Cambridge, MA 02139 USA; MIT, Ctr Space Res, Cambridge, MA 02139 USA; MIT, Dept Phys, Cambridge, MA 02139 USA; Univ Cambridge, Inst Astron, Cambridge CB3 OHA, England; Max Planck Inst Astrophys, D-85741 Garching, Germany
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