Статья

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

A. C. FabianInstitute of Astronomy, Madingley Road, Cambridge CB3 0HADan WilkinsInstitute of Astronomy, Madingley Road, Cambridge CB3 0HAJ. M. MïllerDepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109, USAR. C. ReisDepartment of Astronomy, University of Michigan, Ann Arbor, MI 48109, USAC. S. ReynoldsDepartment of Astronomy, University of Maryland, College Park, MD 20742, USAEdward M. CackettDepartment of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USAMichael A. NowakKavli Institute for Astrophysics and Space Research, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USAG. G. PooleyCavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HEK. PottschmidtCenter for Space Sciemce and Technology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USAJ. S. SandersInstitute of Astronomy, Madingley Road, Cambridge CB3 0HAR. R. RossPhysics Department, College of the Holy Cross, Worcester, MA 01610, USAJ. WilmsDr Karl-Remeis-Sternwarte and Erlangen Center for Astroparticle Physics, Sternwartstr. 7, 96049 Bamberg, Germany

2012en

ABI

Аннотация

The spin of Cygnus X-1 is measured by fitting reflection models to Suzaku data covering the energy band 0.9–400 keV. The inner radius of the accretion disc is found to lie within 2 gravitational radii (rg=GM/c²), and a value of 0.97⁺⁰.⁰¹⁴₋₀.₀₂ 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 23.7⁺⁶.⁷₋₅.₄⁠, which is consistent with the recent optical measurement of the binary system inclination by Orosz et al. of 27°± 0°.8. 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.

Перевод пока недоступен

Идентификаторы

DOI: 10.13016/m2u8qz-eqbf

Цитирования и источники

Цитирований: 3Использованных источников: 0

Показатели — AkademScholar