Open AccessApplication of a relativistic accretion disc model to X‐ray spectra of LMC X‐1 and GRO J1655‐40
Author(s) -
Gierliński Marek,
MaciołekNiedźwiecki Andrzej,
Ebisawa Ken
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04540.x
Subject(s) - physics , black body radiation , astrophysics , accretion (finance) , black hole (networking) , rotating black hole , accretion disc , spectral line , radius , x ray binary , photon , astronomy , neutron star , optics , radiation , computer network , routing protocol , routing (electronic design automation) , computer science , computer security , link state routing protocol
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 0.68 a 0.88 . Accretion discs in both sources are radiation‐pressure dominated. We do not find Compton reflection features in the spectra of any of these objects.