The Delta Resonance in the Neutrino Sky

Fuente: arXiv
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Main Authors: Zathul, Arifa Khatee, Fang, Ke, Halzen, Francis, Hooper, Dan
Format: Preprint
Published: 2026
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author Zathul, Arifa Khatee
Fang, Ke
Halzen, Francis
Hooper, Dan
author_facet Zathul, Arifa Khatee
Fang, Ke
Halzen, Francis
Hooper, Dan
contents Recent measurements of the diffuse cosmic neutrino flux by IceCube show evidence for a spectral break at an energy near $E_ν\sim 30$ TeV. In this letter, we suggest that this feature may be due to the $Δ$-baryon resonance in $pγ$ interactions. We show that the measured spectrum, including the observed break, can be naturally accommodated by a flux of protons accelerated with a spectrum $dN_p /dE_p \propto E_p^{-3.1}$ interacting with X-rays of typical energy $E_γ \sim 0.3\,{\rm keV}$. We also point out that the presence of this spectral break significantly reduces the contribution of neutrino sources to the isotropic gamma-ray background, alleviating the longstanding tension between these measurements. In the $Δ$-resonance scenario, the gamma rays accompanying neutrino production cascade down to MeV-GeV energies and contribute at the $\sim 10\%$ level to the isotropic gamma-ray background at $\sim 3$~GeV. If our proposal is realized, it may imply that we have identified the dominant sources that produce the extragalactic cosmic rays.
format Preprint
id arxiv_https___arxiv_org_abs_2606_00249
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Delta Resonance in the Neutrino Sky
Zathul, Arifa Khatee
Fang, Ke
Halzen, Francis
Hooper, Dan
High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
Recent measurements of the diffuse cosmic neutrino flux by IceCube show evidence for a spectral break at an energy near $E_ν\sim 30$ TeV. In this letter, we suggest that this feature may be due to the $Δ$-baryon resonance in $pγ$ interactions. We show that the measured spectrum, including the observed break, can be naturally accommodated by a flux of protons accelerated with a spectrum $dN_p /dE_p \propto E_p^{-3.1}$ interacting with X-rays of typical energy $E_γ \sim 0.3\,{\rm keV}$. We also point out that the presence of this spectral break significantly reduces the contribution of neutrino sources to the isotropic gamma-ray background, alleviating the longstanding tension between these measurements. In the $Δ$-resonance scenario, the gamma rays accompanying neutrino production cascade down to MeV-GeV energies and contribute at the $\sim 10\%$ level to the isotropic gamma-ray background at $\sim 3$~GeV. If our proposal is realized, it may imply that we have identified the dominant sources that produce the extragalactic cosmic rays.
title The Delta Resonance in the Neutrino Sky
topic High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2606.00249