Journal Article

Determining the spin of two stellar-mass black holes from disc reflection signatures

R. C. Reis, A. C. Fabian, R. R. Ross and J. M. Miller

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 395, issue 3, pages 1257-1264
Published in print May 2009 | ISSN: 0035-8711
Published online May 2009 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2009.14622.x
Determining the spin of two stellar-mass black holes from disc reflection signatures

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We present measurements of the dimensionless spin parameters and inner-disc inclination of two stellar-mass black holes. The spin parameter of SWIFT J1753.5−0127 and GRO J1655−40 is estimated by modelling the strong reflection signatures present in their XMM–Newton observations. Using a newly developed, self-consistent reflection model which includes the blackbody radiation of the disc as well as the effect of Comptonization, blurred with a relativistic line function, we infer the spin parameter of SWIFT J1753.5−0127 to be 0.76+0.11−0.15. The inclination of this system is estimated at 55°+2−7. For GRO J1655−40, we find that the disc is significantly misaligned to the orbital plane, with an innermost inclination of 30°+5−10. Allowing the inclination to be a free parameter, we find a lower limit for the spin of 0.90, this value increases to that of a maximal rotating black hole when the inclination is set to that of the orbital plane of J1655−40. Our technique is independent of the black hole mass and distance, uncertainties in which are among the main contributors to the spin uncertainty in previous works.

Keywords: accretion, accretion discs; black hole physics; X-rays: individual: J1753.5−0127, J1655−40

Journal Article.  6088 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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