The observation of the shadow of the supermassive black hole M87* by the Event Horizon Telescope (EHT) is sensitive to the spacetime geometry near the circular photon orbit and beyond, and it thus has the potential to test general relativity in the strong field regime. Obstacles to this program, however, include degeneracies between putative deviations from general relativity and both the description of the accretion flow and the uncertainties on "calibration parameters," such as, e.g., the mass and spin of the black hole. In this work, we introduce a formalism, based on a principal component analysis, capable of reconstructing the black hole metric (i.e., the "signal") in an agnostic way, while subtracting the "foreground" due to the uncertainties in the calibration parameters and the modeling of the accretion flow. We apply our technique to simulated mock data for spherically symmetric black holes surrounded by a thick accretion disk. We show that separation of signal and foreground may be possible with next generation EHT-like experiments.

Separating astrophysics and geometry in black hole images / Lara, Guillermo; Völkel, Sebastian H.; Barausse, Enrico. - In: PHYSICAL REVIEW D. - ISSN 2470-0010. - 104:12(2021), pp. 1-12. [10.1103/PhysRevD.104.124041]

Separating astrophysics and geometry in black hole images

Lara, Guillermo
;
Barausse, Enrico
2021-01-01

Abstract

The observation of the shadow of the supermassive black hole M87* by the Event Horizon Telescope (EHT) is sensitive to the spacetime geometry near the circular photon orbit and beyond, and it thus has the potential to test general relativity in the strong field regime. Obstacles to this program, however, include degeneracies between putative deviations from general relativity and both the description of the accretion flow and the uncertainties on "calibration parameters," such as, e.g., the mass and spin of the black hole. In this work, we introduce a formalism, based on a principal component analysis, capable of reconstructing the black hole metric (i.e., the "signal") in an agnostic way, while subtracting the "foreground" due to the uncertainties in the calibration parameters and the modeling of the accretion flow. We apply our technique to simulated mock data for spherically symmetric black holes surrounded by a thick accretion disk. We show that separation of signal and foreground may be possible with next generation EHT-like experiments.
2021
104
12
1
12
124041
10.1103/PhysRevD.104.124041
https://arxiv.org/abs/2110.00026
Lara, Guillermo; Völkel, Sebastian H.; Barausse, Enrico
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/125609
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