On the determination of the spin of the black hole in Cyg X-1 from X-ray reflection spectra

Fabian AC, Wilkins DR, Miller JM, Reis RC, Reynolds CS, Cackett EM, Nowak MA, Pooley GG, Pottschmidt K, Sanders JS, Ross RR, Wilms J (2012)

Publication Status: Published

Publication Type: Journal article

Publication year: 2012

Journal

Monthly Notices of the Royal Astronomical Society Oxford University Press

Publisher: WILEY-BLACKWELL

Book Volume: 424

Pages Range: 217-223

Journal Issue: 1

DOI: 10.1111/j.1365-2966.2012.21185.x

Abstract

The spin of Cygnus X-1 is measured by fitting reflection models to Suzaku data covering the energy band 0.9400 keV. The inner radius of the accretion disc is found to lie within 2 gravitational radii (rg=GM/c2), and a value of is obtained for the dimensionless black hole spin. This agrees with recent measurements using the continuum fitting method by Gou et al. and of the broad iron line by Duro et al. The disc inclination is measured at , which is consistent with the recent optical measurement of the binary system inclination by Orosz et al. of 27 degrees +/- 08. We pay special attention to the emissivity profile caused by irradiation of the inner disc by the hard power-law source. The X-ray observations and simulations show that the index q of that profile deviates from the commonly used, Newtonian, value of 3 within 3rg, steepening considerably within 2rg, as expected in the strong gravity regime.

Authors with CRIS profile

Jörn Wilms Professur für Astronomie und Astrophysik

Involved external institutions

University of Cambridge GB United Kingdom (GB) National Aeronautics and Space Administration (NASA) US United States (USA) (US) University of Maryland US United States (USA) (US) University of Michigan US United States (USA) (US) Massachusetts Institute of Technology (MIT) US United States (USA) (US) College of the Holy Cross US United States (USA) (US)

How to cite

APA:

Fabian, A.C., Wilkins, D.R., Miller, J.M., Reis, R.C., Reynolds, C.S., Cackett, E.M.,... Wilms, J. (2012). On the determination of the spin of the black hole in Cyg X-1 from X-ray reflection spectra. Monthly Notices of the Royal Astronomical Society, 424(1), 217-223. https://doi.org/10.1111/j.1365-2966.2012.21185.x

MLA:

Fabian, A. C., et al. "On the determination of the spin of the black hole in Cyg X-1 from X-ray reflection spectra." Monthly Notices of the Royal Astronomical Society 424.1 (2012): 217-223.

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