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Published April 10, 2019 | Published
Journal Article Open

Toward Precision Tests of General Relativity with Black Hole X-Ray Reflection Spectroscopy


Astrophysical black hole systems are the ideal laboratories for testing Einstein's theory of gravity in the strong field regime. We have recently developed a framework that uses the reflection spectrum of black hole systems to perform precision tests of general relativity by testing the Kerr black hole hypothesis. In this paper, we analyze XMM-Newton and NuSTAR observations of the supermassive black hole in the Seyfert 1 galaxy MCG–06–30–15 with our disk reflection model. We consider the Johannsen metric with the deformation parameters α_(13) and α_(22), which quantify deviations from the Kerr metric. For α_(22) = 0, we obtain the black hole spin 0.928 < a* < 0.983 and -0.44 < α_(13) < 0.15. For α_(13) = 0, we obtain 0.885 < a* < 0.987 and -0.12 < α_(22) < 1.05 . The Kerr solution is recovered for α_(13) = α_(22) = 0. Thus, our results include the Kerr solution within statistical uncertainties. Systematic uncertainties are difficult to account for, and we discuss some issues in this regard.

Additional Information

© 2019 The American Astronomical Society. Received 2018 November 23; revised 2019 March 8; accepted 2019 March 8; published 2019 April 16. A.T. thanks Laura Brenneman for useful discussions on MCG–06–30–15. This work was supported by the National Natural Science Foundation of China (NSFC), grant No. U1531117, and Fudan University, grant No. IDH1512060. A.T. also acknowledges support from the China Scholarship Council (CSC), grant No. 2016GXZR89. S.N. acknowledges support from the Excellence Initiative at Eberhard-Karls Universität Tübingen. A.B.A. also acknowledges the support from the Shanghai Government Scholarship (SGS). J.A.G. acknowledges support from the Alexander von Humboldt Foundation.

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August 19, 2023
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