Re-estimating the Spin Parameter of the Black Hole in Cygnus X-1

Re-estimating the Spin Parameter of the Black Hole in Cygnus X-1

Cygnus X-1 is a well-studied persistent black hole X-ray binary. Recently, the three parameters needed to estimate the black hole spin of this system, namely the black hole mass M, the orbital inclination i, and the source distance D, have been updated. In this work we redetermine the spin parameter...

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Bibliographic Details
Main Authors: Zhao, X., Gou, L., Dong, Y., Zheng, X., Steiner, J.F., Miller-Jones, James, Bahramian, Arash, Orosz, J.A., Feng, Y.
Format: Journal Article
Language:English
Published: IOP PUBLISHING LTD 2021
Subjects:
Science & Technology
Physical Sciences
Astronomy & Astrophysics
X-ray binary stars
Black hole physics
High energy astrophysics
astro-ph.HE
Online Access:http://purl.org/au-research/grants/arc/FT140101082
http://hdl.handle.net/20.500.11937/91526
Description
Summary:Cygnus X-1 is a well-studied persistent black hole X-ray binary. Recently, the three parameters needed to estimate the black hole spin of this system, namely the black hole mass M, the orbital inclination i, and the source distance D, have been updated. In this work we redetermine the spin parameter using the continuum-fitting technique for those updated parameter values. Based on the assumption that the spin axis of the black hole is aligned with the orbital plane, we fit the thermal disk component to a fully relativistic thin accretion disk model. The error in the spin estimate arising from the combined observational uncertainties is obtained via Monte Carlo simulations. We demonstrate that, without considering the counteracting torque effect, the new spin parameter is constrained to be a ∗ > 0.9985 (3σ), which confirms that the spin of the black hole in Cygnus X-1 is extreme.

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