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Titolo:
A complete relativistic ionized accretion disc in Cygnus X-1
Autore:
Young, AJ; Fabian, AC; Ross, RR; Tanaka, Y;
Indirizzi:
Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England Univ Cambridge Cambridge England CB3 0HA ron, Cambridge CB3 0HA, England Coll Holy Cross, Dept Phys, Worcester, MA 01610 USA Coll Holy Cross Worcester MA USA 01610 Dept Phys, Worcester, MA 01610 USA Max Planck Inst Extraterr Phys, D-85740 Garching, Germany Max Planck Inst Extraterr Phys Garching Germany D-85740 arching, Germany
Titolo Testata:
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
fascicolo: 3, volume: 325, anno: 2001,
pagine: 1045 - 1052
SICI:
0035-8711(20010811)325:3<1045:ACRIAD>2.0.ZU;2-3
Fonte:
ISI
Lingua:
ENG
Soggetto:
X-RAY REFLECTION; ACTIVE GALACTIC NUCLEI; BLACK-HOLE; SPECTRUM; CORONA; STATE;
Keywords:
accretion, accretion discs; black hole physics; binaries : close; stars : individual : Cyg X-1; X-rays : general; X-rays : stars;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
26
Recensione:
Indirizzi per estratti:
Indirizzo: Young, AJ Univ Maryland, Dept Astron, College Pk, MD 20742 USA Univ Maryland College Pk MD USA 20742 College Pk, MD 20742 USA
Citazione:
A.J. Young et al., "A complete relativistic ionized accretion disc in Cygnus X-1", M NOT R AST, 325(3), 2001, pp. 1045-1052

Abstract

The galactic black hole candidate Cygnus X-1 is observed to be in one of two X-ray spectral states: either the low/hard (low soft X-ray flux and a flat power-law tail) or high/soft (high blackbody-like soft X-ray flux and a steep power-law tail) state. The physical origin of these two states is unclear. We present here a model of an ionized accretion disc, the spectrum ofwhich is blurred by relativistic effects, and fit it to the ASCA, Ginga and EXOSAT data of Cygnus X-1 in both spectral states. We confirm that relativistic blurring provides a much better fit to the low/hard state data and, contrary to some previous results, find the data of both states to be consistent with an ionized thin accretion disc with a reflected fraction of unity extending to the innermost stable circular orbit around the black hole. Our model is an alternative to those that, in the low/hard state, require the accretion disc to be truncated at a few tens of Schwarzschild radii, within which there is a Thomson-thin, hot accretion flow. We suggest a mechanism that may cause the changes in spectral state.

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Documento generato il 10/07/20 alle ore 00:03:48