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Researchers propose that a spectral break observed at approximately 30 TeV in the diffuse cosmic neutrino flux detected by IceCube may result from the Delta-baryon resonance occurring when protons interact with X-ray photons. Their model suggests that protons accelerated with a specific energy spectrum interact with X-rays of around 0.3 keV energy to produce this feature. This mechanism also resolves a long-standing inconsistency between neutrino measurements and the isotropic gamma-ray background, as the accompanying gamma rays cascade to lower energies and contribute only about 10% to the background at 3 GeV.
Why it matters
If confirmed, this finding could identify the dominant sources of extragalactic cosmic rays, solving a major puzzle in astrophysics. The proposed mechanism provides a unified explanation for both neutrino observations and gamma-ray measurements, potentially transforming our understanding of high-energy particle acceleration in the universe.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: Recent measurements of the diffuse cosmic neutrino flux by IceCube show evidence for a spectral break at an energy near $E_nu sim 30$ TeV. In this letter, we suggest that this feature may be due to the $Delta$-baryon resonance in $pgamma$ 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 $E_{gamma} sim 0.3,{rm keV}$. 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 $Delta$-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.