Journal
ASTRONOMY & ASTROPHYSICS
Volume 589, Issue -, Pages -Publisher
EDP SCIENCES S A
DOI: 10.1051/0004-6361/201424740
Keywords
X-rays: binaries; black hole physics; gravitation
Categories
Funding
- European Commission [ITN 215212]
- Bundesministerium fur Wirtschaft und Technologie under Deutsches Zentrum fur Luft- und Raumfahrt [50OR0701, 50OR1007, 50OR1113]
- NASA through the Smithsonian Astrophysical Observatory (SAO) [SV3-73016]
- NASA [NAS8-03060, NNX13AE98G]
- DFG Cluster of Excellence Origin and Structure of the Universe
- French National Research Agency [ANR-12-BS05-0009]
- NASA [475447, NNX13AE98G] Funding Source: Federal RePORTER
- Agence Nationale de la Recherche (ANR) [ANR-12-BS05-0009] Funding Source: Agence Nationale de la Recherche (ANR)
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We report on the analysis of the broad Fe K alpha line feature of Cyg X-1 in the spectra of four simultaneous hard intermediate state observations made with the X-ray Multiple Mirror mission (XMM-Newton), the Rossi X-ray Timing Explorer (RXTE), and the International Gamma-Ray Astrophysics Laboratory (INTEGRAL). The high quality of the XMM-Newton data taken in the Modified Timing Mode of the EPIC-pn camera provides a great opportunity to investigate the broadened Fe K alpha reflection line at 6.4 keV with a very high signal to noise ratio. The 4-500 keV energy range is used to constrain the underlying continuum and the reflection at higher energies. We first investigate the data by applying a phenomenological model that consists of the sum of an exponentially cutoff power law and relativistically smeared reflection. Additionally, we apply a more physical approach and model the irradiation of the accretion disk directly from the lamp post geometry. All four observations show consistent values for the black hole parameters with a spin of a similar to 0.9, in agreement with recent measurements from reflection and disk continuum fitting. The inclination is found to be i similar to 30 degrees, consistent with the orbital inclination and different from inclination measurements made during the soft state, which show a higher inclination. We speculate that the difference between the inclination measurements is due to changes in the inner region of the accretion disk.
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