Application of a relativistic accretion disc model to X-ray spectra of LMC X-1 and GRO J1655-40

Gierlinski, M.; Maciołek-Niedźwiecki, A.; Ebisawa, K.

Abstract

We present a general relativistic accretion disc model and its application to the soft-state X-ray spectra of black hole binaries. The model assumes a flat, optically thick disc around a rotating Kerr black hole. The disc locally radiates away the dissipated energy as a blackbody. Special and general relativistic effects influencing photons emitted by the disc are taken into account. The emerging spectrum, as seen by a distant observer, is parametrized by the black hole mass and spin, the accretion rate, the disc inclination angle and the inner disc radius. We fit the ASCA soft-state X-ray spectra of LMC X-1 and GRO J1655-40 by this model. We find that, having additional limits on the black hole mass and inclination angle from optical/UV observations, we can constrain the black hole spin from X-ray data. In LMC X-1 the constraint is weak, and we can only rule out the maximally rotating black hole. In GRO J1655-40 we can limit the spin much better, and we find 0.68a0.88. Accretion discs in both sources are radiation-pressure dominated. We do not find Compton reflection features in the spectra of any of these objects.

Citation

Gierlinski, M., Maciołek-Niedźwiecki, A., & Ebisawa, K. (2001). Application of a relativistic accretion disc model to X-ray spectra of LMC X-1 and GRO J1655-40. Monthly Notices of the Royal Astronomical Society, 325(3), 1253-1265. https://doi.org/10.1046/j.1365-8711.2001.04540.x

• Journal Article Type: Article
• Publication Date: 2001-08
• Deposit Date: Apr 28, 2008
• Publicly Available Date: Apr 28, 2008
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 325
• Issue: 3
• Pages: 1253-1265
• DOI: https://doi.org/10.1046/j.1365-8711.2001.04540.x
• Keywords: Accretion discs, Relativity, Stars.
• Public URL: https://durham-repository.worktribe.com/output/1606297