Latest νs from the Earliest Galaxies: Probing neutrino self-interactions with JWST
Abstract
Our Universe serves as a complementary laboratory for particle physics interactions. One intriguing possibility is that neutrinos may have beyond-the-Standard-Model (BSM) self-interactions, which can delay their free streaming and have an observable effect across different redshifts. Such interactions can induce scale-dependent changes in the matter power spectrum. The James Webb Space Telescope (JWST) has opened up a new window onto the early Universe by discovering a large population of high-redshift galaxies up to z ∼ 15 and various probable galaxy candidates at even higher redshifts, between z ∼ 15−30. Such high-redshift observations can probe the matter power spectrum on small scales, since structure formation is hierarchical and the structures hosting these high-redshift galaxies are therefore expected to be small. We, for the first time, use the UV luminosity function data from JWST and combine them with the Planck CMB data to probe neutrino self-interactions (νSI). If only one neutrino flavor experiences such BSM interactions, then Planck + JWST data give a 95% C.L. upper limit on Log10(Geff/MeV−2) ≈ −2.75 and when all three flavors are interacting, the corresponding constraint becomes ≲ −3.41; both stronger than those obtained using only Planck data. Our results highlight the power of this new observable, the high-redshift UV luminosity function from JWST as a complementary probe to terrestrial experiments, showing that small-scale observables can open a new window onto smaller neutrino self-interaction strengths.
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BibTeX
@misc{mondol2026latest,
title = {{Latest $ν$s from the Earliest Galaxies: Probing neutrino self-interactions with JWST}},
author = {Ranjini Mondol and Priyank Parashari and Anirban Das and Vera Gluscevic and Ranjan Laha},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.07013},
eprint = {2611.07013},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.07013},
}
RIS
TY - UNPB
TI - Latest νs from the Earliest Galaxies: Probing neutrino self-interactions with JWST
AU - Ranjini Mondol
AU - Priyank Parashari
AU - Anirban Das
AU - Vera Gluscevic
AU - Ranjan Laha
PY - 2026
DA - 2026/11/04
PB - arXiv
DO - 10.48550/arxiv.2611.07013
UR - https://arxiv.org/abs/2611.07013
AB - Our Universe serves as a complementary laboratory for particle physics interactions. One intriguing possibility is that neutrinos may have beyond-the-Standard-Model (BSM) self-interactions, which can delay their free streaming and have an observable effect across different redshifts. Such interactions can induce scale-dependent changes in the matter power spectrum. The James Webb Space Telescope (JWST) has opened up a new window onto the early Universe by discovering a large population of high-redshift galaxies up to z ∼ 15 and various probable galaxy candidates at even higher redshifts, between z ∼ 15−30. Such high-redshift observations can probe the matter power spectrum on small scales, since structure formation is hierarchical and the structures hosting these high-redshift galaxies are therefore expected to be small. We, for the first time, use the UV luminosity function data from JWST and combine them with the Planck CMB data to probe neutrino self-interactions (νSI). If only one neutrino flavor experiences such BSM interactions, then Planck + JWST data give a 95% C.L. upper limit on Log_10(G_eff/MeV^−2) ≈ −2.75 and when all three flavors are interacting, the corresponding constraint becomes ≲ −3.41; both stronger than those obtained using only Planck data. Our results highlight the power of this new observable, the high-redshift UV luminosity function from JWST as a complementary probe to terrestrial experiments, showing that small-scale observables can open a new window onto smaller neutrino self-interaction strengths.
ER -