Oscillations of the black hole photon ring as a probe of ultralight dilaton fields

Fuente: arXiv
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Main Authors: Li, Chunlong, Chen, Chao, Chew, Xiao Yan
Format: Preprint
Published: 2025
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author Li, Chunlong
Chen, Chao
Chew, Xiao Yan
author_facet Li, Chunlong
Chen, Chao
Chew, Xiao Yan
contents Advancements of very long baseline interferometry (VLBI) have facilitated unprecedented probing of superradiant phenomena in the vicinities of supermassive black holes (SMBHs), establishing an ideal laboratory to detect ultralight bosons beyond the Standard Model. In this study, we delve into how ultralight dilaton clouds, formed via SMBH superradiance, impact the black hole photon rings. Our focus is on the dilaton-electromagnetic coupling term of the form $f(ϕ)F_{μν}F^{μν}$. By integrating geometric optics with plasma refractive effects in accretion environments, we demonstrate that the dilaton cloud dynamically alters the plasma frequency. Through systematic ray-tracing simulations covering a range of photon frequencies and dilaton coupling strengths, we reveal a photon ring oscillation that follows the period of that of the dilaton field. As the dilaton mass increases, this oscillation becomes suppressed due to the washout effect of the dilaton-induced correction term over the light path integration. We further evaluated the observability of such dilaton-induced photon ring oscillations with current radio interferometric capabilities. Our estimates indicate that this effect could potentially constrain the dilaton-photon coupling to $g_{ϕγ}\lesssim 10^{-11}\text{GeV}^{-1}$ for dilaton masses $μ\lesssim 10^{-18}\,\mathrm{eV}$.
format Preprint
id arxiv_https___arxiv_org_abs_2503_07947
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Oscillations of the black hole photon ring as a probe of ultralight dilaton fields
Li, Chunlong
Chen, Chao
Chew, Xiao Yan
General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
Advancements of very long baseline interferometry (VLBI) have facilitated unprecedented probing of superradiant phenomena in the vicinities of supermassive black holes (SMBHs), establishing an ideal laboratory to detect ultralight bosons beyond the Standard Model. In this study, we delve into how ultralight dilaton clouds, formed via SMBH superradiance, impact the black hole photon rings. Our focus is on the dilaton-electromagnetic coupling term of the form $f(ϕ)F_{μν}F^{μν}$. By integrating geometric optics with plasma refractive effects in accretion environments, we demonstrate that the dilaton cloud dynamically alters the plasma frequency. Through systematic ray-tracing simulations covering a range of photon frequencies and dilaton coupling strengths, we reveal a photon ring oscillation that follows the period of that of the dilaton field. As the dilaton mass increases, this oscillation becomes suppressed due to the washout effect of the dilaton-induced correction term over the light path integration. We further evaluated the observability of such dilaton-induced photon ring oscillations with current radio interferometric capabilities. Our estimates indicate that this effect could potentially constrain the dilaton-photon coupling to $g_{ϕγ}\lesssim 10^{-11}\text{GeV}^{-1}$ for dilaton masses $μ\lesssim 10^{-18}\,\mathrm{eV}$.
title Oscillations of the black hole photon ring as a probe of ultralight dilaton fields
topic General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2503.07947