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The Orbital Period of the Wolf-Rayet Binary IC 10 X-1: Dynamic Evidence that the Compact Object Is a Black Hole

Prestwich, A.H.; Kilgard, R.; Crowther, P.A.; Carpano, S.; Pollock, A.M.T.; Zezas, A.; Saar, S.H.; Roberts, T.P.; Ward, M.J.

The Orbital Period of the Wolf-Rayet Binary IC 10 X-1: Dynamic Evidence that the Compact Object Is a Black Hole Thumbnail


Authors

A.H. Prestwich

R. Kilgard

P.A. Crowther

S. Carpano

A.M.T. Pollock

A. Zezas

S.H. Saar

M.J. Ward



Abstract

IC 10 X-1 is a bright (LX = 1038 ergs s-1) variable X-ray source in the Local Group starburst galaxy IC 10. The most plausible optical counterpart is a luminous Wolf-Rayet star, making IC 10 X-1 a rare example of a Wolf-Rayet X-ray binary. In this Letter, we report on the detection of an X-ray orbital period for IC 10 X-1 of 34.4 hr. This result, combined with a reexamination of optical spectra, allows us to determine a mass function for the system of f(M) = 7.8 M☉ and a probable mass for the compact object of 24-33 M☉. If this analysis is correct, the compact object is the most massive stellar-mass black hole known. We further show that the observed period is inconsistent with Roche lobe overflow, suggesting that the binary is detached and that the black hole is accreting the wind of the Wolf-Rayet star. The observed mass-loss rate of [MAC92] 17A is sufficient to power the X-ray luminosity of IC 10 X-1.

Citation

Prestwich, A., Kilgard, R., Crowther, P., Carpano, S., Pollock, A., Zezas, A., …Ward, M. (2007). The Orbital Period of the Wolf-Rayet Binary IC 10 X-1: Dynamic Evidence that the Compact Object Is a Black Hole. Astrophysical Journal Letters, 669(1), L21-L24. https://doi.org/10.1086/523755

Journal Article Type Article
Publication Date Nov 1, 2007
Deposit Date Feb 20, 2014
Publicly Available Date Mar 29, 2024
Journal Astrophysical Journal Letters
Print ISSN 2041-8205
Electronic ISSN 2041-8213
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 669
Issue 1
Pages L21-L24
DOI https://doi.org/10.1086/523755
Keywords Galaxies, Starburst, Stars, Wolf-Rayet, X-rays, Binaries.

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Copyright Statement
© 2007. The American Astronomical Society. All rights reserved.





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