THE EXTREME SPIN OF THE BLACK HOLE IN CYGNUS X-1

By Lijun Gou, J. E. McClintock, M. J. Reid, J. Orosz, J. Steiner, Ramesh Narayan, J. Xiang, Ronald A. Remillard, K. Arnaud, S. Davis. 2011

195 citations recorded by the source corpus.

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.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7d5866b95066a70d59899999c67da3312468261d

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Nuclear and High Energy Physics

Citations in the corpus

Irradiation of an accretion disc by a jet: general properties and implications for spin measurements of black holes (2013, result): “Where a broad line is observed, the results of continuum spin measurements and line measurements agree (e.g., Gou et al. 2011 and Duro et al. 2011 for the case of Cyg X1).”
Measuring Black Hole Spin Using X-Ray Reflection Spectroscopy (2013, background): “For Cygnus X-1, there is now general agreement between reflectionbased measurements (Fabian et al. 2012) and CF-measurements (Gou et al. 2011) that the black hole is a rapid spinner, a > 0.95.”
THE TRIGONOMETRIC PARALLAX OF CYGNUS X-1 (2011, methodology): “With the required, accurate values of M, i, and D in hand, in Paper III we proceed (Gou et al. 2011) to model the X-ray continuum spectrum and determine the spin of the BH. BH spin can be determined because the measured X-ray spectrum from the accretion disk is dominated by radiation coming from…”
THE MASS OF THE BLACK HOLE IN CYGNUS X-1 (2011, methodology): “There are soft and hard states of Cygnus X-1 (e.g., Gou et al. 2011).”
Microarcsecond Radio Astrometry (2013, background): “This revealed that black hole spin is near maximal and, since the binary is too young for accretion to have appreciably spun up the black hole, most of the spin angular momentum is probably natal (Gou et al. 2011).”
The Masses and Spins of Neutron Stars and Stellar-Mass Black Holes (2014, methodology): “The spin of Cygnus X-1 was recently measured well using the disk continuum [296] and later via reflection [297, 298], and commensurate values were again obtained.”
Precise mass and spin measurements for a stellar-mass black hole through X-ray timing: the case of GRO J1655-40 (2013, result): “For instance, recent results from the continuum fitting method on Cyg X-1 show that it harbours an almost maximally rotating BH (spin >0.95, Gou et al. 2011).”
Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets (2013, background): “By contrast, the three remaining persistent systems – M33 X-7, LMC X-1 and Cyg X-1 – have well-determined values of both mass and spin (see Section 6).”