Following up on a recent analysis by Psaltis et al (2020 Phys. Rev. Lett. 125 141104), we show that the observed shadow size of M87* can be used to unambiguously and robustly constrain the black hole geometry in the vicinity of the circular photon orbit. Constraints on the post-Newtonian weak-field expansion of the black hole's metric are instead more subtle to obtain and interpret, as they rely on combining the shadow-size measurement with suitable theoretical priors. We provide examples showing that post-Newtonian constraints resulting from shadow-size measurements should be handled with extreme care. We also discuss the similarities and complementarity between the EHT shadow measurements and black-hole gravitational quasi-normal modes.

EHT tests of the strong-field regime of general relativity / Völkel, Sebastian H.; Barausse, Enrico; Franchini, Nicola; Broderick, Avery E.. - In: CLASSICAL AND QUANTUM GRAVITY. - ISSN 0264-9381. - 38:21(2021), pp. 1-12. [10.1088/1361-6382/ac27ed]

EHT tests of the strong-field regime of general relativity

Barausse, Enrico;Franchini, Nicola;
2021-01-01

Abstract

Following up on a recent analysis by Psaltis et al (2020 Phys. Rev. Lett. 125 141104), we show that the observed shadow size of M87* can be used to unambiguously and robustly constrain the black hole geometry in the vicinity of the circular photon orbit. Constraints on the post-Newtonian weak-field expansion of the black hole's metric are instead more subtle to obtain and interpret, as they rely on combining the shadow-size measurement with suitable theoretical priors. We provide examples showing that post-Newtonian constraints resulting from shadow-size measurements should be handled with extreme care. We also discuss the similarities and complementarity between the EHT shadow measurements and black-hole gravitational quasi-normal modes.
2021
38
21
1
12
21LT01
10.1088/1361-6382/ac27ed
https://arxiv.org/abs/2011.06812
Völkel, Sebastian H.; Barausse, Enrico; Franchini, Nicola; Broderick, Avery E.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/124871
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