Confirmation Via the Continuum-Fitting Method that the Spin of the Black Hole in Cygnus X-1 is Extreme

Дата и время публикации : 2013-08-22T04:33:34Z

Авторы публикации и институты :
Lijun Gou
Jeffrey E. McClintock
Ronald A. Remillard
James F. Steiner
Mark J. Reid
Jerome A. Orosz
Ramesh Narayan
Manfred Hanke
Javier García

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 13 pages in emulated ApJ format, including 5 figures and 4 tables, ApJ submitted. arXiv admin note: text overlap with arXiv:1106.3690
Первичная категория: astro-ph.HE

Все категории : astro-ph.HE, astro-ph.SR, hep-th

Краткий обзор статьи: In Gou et al. (2011), we reported that the black hole primary in the X-ray binary Cygnus X-1 is a near-extreme Kerr black hole with a spin parameter a*>0.95(3{sigma}). We confirm this result while setting a new and more stringent limit: a*>0.983 at the 3{sigma}(99.7%) level of confidence. The earlier work, which was based on an analysis of all three useful spectra that were then available, was possibly biased by the presence in these spectra of a relatively strong Compton power-law component: The fraction of the thermal seed photons scattered into the power law was f_s=23-31%, while the upper limit for reliable application of the continuum-fitting method is f_s<25%. We have subsequently obtained six additional spectra of Cygnus X-1 suitable for the measurement of spin. Five of these spectra are of high quality with f_s in the range 10% to 19%, a regime where the continuum-fitting method has been shown to deliver very reliable results. Individually, the six spectra give lower limits on the spin parameter that range from a*>0.95 to a*>0.98, allowing us to conservatively conclude that the spin of the black hole is a*>0.983 (3{sigma}).

Category: Physics