Testing general relativity's no-hair theorem with x-ray observations of black holes

Hoormann, Janie K., Beheshtipour, Banafsheh and Krawczynski, Henric (2016) Testing general relativity's no-hair theorem with x-ray observations of black holes. Physical Review D, 93 4: . doi:10.1103/PhysRevD.93.044020

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Author Hoormann, Janie K.
Beheshtipour, Banafsheh
Krawczynski, Henric
Title Testing general relativity's no-hair theorem with x-ray observations of black holes
Journal name Physical Review D   Check publisher's open access policy
ISSN 2470-0010
2470-0029
Publication date 2016-02-08
Sub-type Article (original research)
DOI 10.1103/PhysRevD.93.044020
Open Access Status File (Publisher version)
Volume 93
Issue 4
Total pages 12
Place of publication College Park, MD, United States
Publisher American Physical Society
Language eng
Abstract Despite its success in the weak gravity regime, general relativity (GR) has yet to be verified in the regime of strong gravity. In this paper, we present the results of detailed ray-tracing simulations aiming at clarifying if the combined information from x-ray spectroscopy, timing, and polarization observations of stellar mass and supermassive black holes can be used to test GR’s no-hair theorem. The latter states that stationary astrophysical black holes are described by the Kerr family of metrics, with the black hole mass and spin being the only free parameters. We use four “non-Kerr metrics,” some phenomenological in nature and others motivated by alternative theories of gravity, and study the observational signatures of deviations from the Kerr metric. Particular attention is given to the case when all the metrics are set to give the same innermost stable circular orbit in quasi–Boyer-Lindquist coordinates. We give a detailed discussion of similarities and differences of the observational signatures predicted for black holes in the Kerr metric and the non-Kerr metrics. We emphasize that even though some regions of the parameter space are nearly degenerate even when combining the information from all observational channels, x-ray observations of very rapidly spinning black holes can be used to exclude large regions of the parameter space of the alternative metrics. Although it proves difficult to distinguish between the Kerr and non-Kerr metrics for some portions of the parameter space, the observations of very rapidly spinning black holes like Cyg X-1 can be used to rule out large regions for several black hole metrics.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ
Additional Notes Article number 044020

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Mathematics and Physics
 
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Created: Thu, 08 Jun 2017, 12:54:03 EST by Janie Hoormann on behalf of Physics