Impact of the cosmic neutrino background on black hole superradiance

Fuente: arXiv
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Main Authors: Lambiase, Gaetano, Poddar, Tanmay Kumar, Visinelli, Luca
Format: Preprint
Published: 2025
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author Lambiase, Gaetano
Poddar, Tanmay Kumar
Visinelli, Luca
author_facet Lambiase, Gaetano
Poddar, Tanmay Kumar
Visinelli, Luca
contents We assess the effect of the Cosmic Neutrino Background (C$ν$B) on superradiant instabilities caused by an ultralight scalar field around spinning black holes (BHs). When the scalar couples to neutrinos via a Yukawa interaction, thermal corrections from the C$ν$B induce a quartic self-interaction and an effective mass term for the scalar. We show that, for Yukawa couplings as small as $y_{ϕν} \sim 10^{-16}$ (for astrophysical BHs) or $10^{-20}$ (for supermassive BHs), the quartic term can quench the instability and set observable bounds, even if the scalar does not constitute dark matter. We assess the robustness of these constraints against several sources of uncertainty, including gravitational focusing of relic neutrinos, galactic clustering, and non-linear backreaction. An enhanced local neutrino density weakens the bounds by up to an order of magnitude compared to a uniform background, yet the induced self-interaction remains strong enough to significantly affect the superradiant dynamics. Our results open a new observational window on neutrino-coupled scalars via BH superradiance.
format Preprint
id arxiv_https___arxiv_org_abs_2503_02940
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Impact of the cosmic neutrino background on black hole superradiance
Lambiase, Gaetano
Poddar, Tanmay Kumar
Visinelli, Luca
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Theory
We assess the effect of the Cosmic Neutrino Background (C$ν$B) on superradiant instabilities caused by an ultralight scalar field around spinning black holes (BHs). When the scalar couples to neutrinos via a Yukawa interaction, thermal corrections from the C$ν$B induce a quartic self-interaction and an effective mass term for the scalar. We show that, for Yukawa couplings as small as $y_{ϕν} \sim 10^{-16}$ (for astrophysical BHs) or $10^{-20}$ (for supermassive BHs), the quartic term can quench the instability and set observable bounds, even if the scalar does not constitute dark matter. We assess the robustness of these constraints against several sources of uncertainty, including gravitational focusing of relic neutrinos, galactic clustering, and non-linear backreaction. An enhanced local neutrino density weakens the bounds by up to an order of magnitude compared to a uniform background, yet the induced self-interaction remains strong enough to significantly affect the superradiant dynamics. Our results open a new observational window on neutrino-coupled scalars via BH superradiance.
title Impact of the cosmic neutrino background on black hole superradiance
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Theory
url https://arxiv.org/abs/2503.02940