The Extreme Spin of the Black Hole in Cygnus X-1
View/ Open
Author
Gou, Lijun
Reid, Mark J.
Orosz, Jerome A.
Steiner, James F.
Remillard, Ronald A.
Arnaud, Keith A.
Davis, Shane W.
Published Version
https://doi.org/10.1088/0004-637X/742/2/85Metadata
Show full item recordCitation
Gou, Lijun, Jeffrey E. McClintock, Mark J. Reid, Jerome A. Orosz, James F. Steiner, Ramesh Narayan, Jingen Xiang, Ronald A. Remillard, Keith A. Arnaud, and Shane W. Davis. 2011. “The Extreme Spin of the Black Hole in Cygnus X-1.” The Astrophysical Journal 742, no. 2: 85.Abstract
The compact primary in the X-ray binary Cygnus X-1 was the first black hole to be established via dynamical observations. We have recently determined accurate values for its mass and distance, and for the orbital inclination angle of the binary. Building on these results, which are based on our favored (asynchronous) dynamical model, we have measured the radius of the inner edge of the black hole's accretion disk by fitting its thermal continuum spectrum to a fully relativistic model of a thin accretion disk. Assuming that the spin axis of the black hole is aligned with the orbital angular momentum vector, we have determined that Cygnus X-1 contains a near-extreme Kerr black hole with a spin parameter a * > 0.95 (3σ). For a less probable (synchronous) dynamical model, we find a * > 0.92 (3σ). In our analysis, we include the uncertainties in black hole mass, orbital inclination angle, and distance, and we also include the uncertainty in the calibration of the absolute flux via the Crab. These four sources of uncertainty totally dominate the error budget. The uncertainties introduced by the thin-disk model we employ are particularly small in this case given the extreme spin of the black hole and the disk's low luminosity.Other Sources
http://arxiv.org/abs/1106.3690Terms of Use
This article is made available under the terms and conditions applicable to Other Posted Material, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#LAACitable link to this page
http://nrs.harvard.edu/urn-3:HUL.InstRepos:13041331
Collections
- FAS Scholarly Articles [18296]
Contact administrator regarding this item (to report mistakes or request changes)