Non-minimal light-curvature couplings and black-hole imaging

Fuente: arXiv
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Main Authors: Carballo-Rubio, Raúl, Delaporte, Héloïse, Eichhorn, Astrid, Fernandes, Pedro G. S.
Format: Preprint
Published: 2025
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_version_ 1866909890448982016
author Carballo-Rubio, Raúl
Delaporte, Héloïse
Eichhorn, Astrid
Fernandes, Pedro G. S.
author_facet Carballo-Rubio, Raúl
Delaporte, Héloïse
Eichhorn, Astrid
Fernandes, Pedro G. S.
contents Non-minimal couplings between the electromagnetic field strength and the spacetime curvature are part of the effective field theory of gravity and matter. They alter the local propagation of light in a significant way if the ratio of spacetime curvature to the non-minimal coupling is of order one. Spacetime curvature can become appreciable around black holes, and yet the effect of non-minimal couplings on electromagnetic observations of black holes remains underexplored. A particular feature of the non-minimal coupling between the electromagnetic field-strength and the Riemann tensor is that it generates two distinct photon rings for different polarizations. Working within the paradigm of lensing bands and focusing on the $n = 1$ lensing band, we illustrate by which diagnostics a modified light propagation may be distinguished from a modified spacetime geometry and how constraints on the value of the non-minimal coupling can be obtained
format Preprint
id arxiv_https___arxiv_org_abs_2505_21431
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Non-minimal light-curvature couplings and black-hole imaging
Carballo-Rubio, Raúl
Delaporte, Héloïse
Eichhorn, Astrid
Fernandes, Pedro G. S.
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
Non-minimal couplings between the electromagnetic field strength and the spacetime curvature are part of the effective field theory of gravity and matter. They alter the local propagation of light in a significant way if the ratio of spacetime curvature to the non-minimal coupling is of order one. Spacetime curvature can become appreciable around black holes, and yet the effect of non-minimal couplings on electromagnetic observations of black holes remains underexplored. A particular feature of the non-minimal coupling between the electromagnetic field-strength and the Riemann tensor is that it generates two distinct photon rings for different polarizations. Working within the paradigm of lensing bands and focusing on the $n = 1$ lensing band, we illustrate by which diagnostics a modified light propagation may be distinguished from a modified spacetime geometry and how constraints on the value of the non-minimal coupling can be obtained
title Non-minimal light-curvature couplings and black-hole imaging
topic High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2505.21431