Testing relativistic accretion disk models with GRO J1655-40

0571139 - ASÚ 2024 RIV US eng J - Journal Article
Yilmaz, Anastasiya - Svoboda, Jiří - Grinberg, V. - Boorman, Peter G. - Bursa, Michal - Dovčiak, Michal
Testing relativistic accretion disk models with GRO J1655-40.
Astronomische Nachrichten. Roč. 344, č. 4 (2023), č. článku e20230019. ISSN 0004-6337. E-ISSN 1521-3994
R&D Projects: GA ČR(CZ) GX21-06825X; GA ČR(CZ) GJ19-05599Y
Institutional support: RVO:67985815
Keywords : accretion * accretion disks * black hole physics
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 0.9, year: 2022
Method of publishing: Limited access
https://doi.org/10.1002/asna.20230019

Black hole X-ray binaries are ideal environments to test the accretion phenomena in the presence of strong gravitational potentials. KERRBB held an important place in the X-ray spectral continuum method for measuring the black hole spin modeling the emission from the innermost regions of the accretion disk. In this work, we present the results of X-ray spectral analysis using publicly available RXTE data of GRO J1655-40 obtained during the 2005 outburst with the two relativistic accretion disk models, KERRBB and KYNBB. Our analysis showed that both models provide identical results with black hole spin measurements, disk temperature, and disk luminosity when the inner edge of the accretion disk is set at the innermost stable circular orbit (ISCO) for the same accretion rates. We could not obtain reasonable fits for similar to 89% of the observations with a fixed black hole spin value at a(*) = 0.7 using both models. Allowing the spin parameter to vary improved the fit statistic significantly with reduced chi(2) values being reduced from10 to 100 to below 2. Both models revealed black hole spin values varying between 0.52 < a(*) < 0.94, which can be interpreted as a variable inner edge of the disk throughout different accretion states.
Permanent Link: https://hdl.handle.net/11104/0345166