2025/07/10 by Maximilian Meier, Brian Clark, Meier, Maximilian +1 · 1 citation
Earth and Planetary Sciences · Environmental Science · Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Earth Systems and Cosmic Evolution #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Insects and Parasite Interactions
paper · pdf · doi:10.48550/arxiv.2507.07497
openalex publication_date 2025/07/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
When ultra-high-energy cosmic rays (UHECRs) interact with ambient photon backgrounds, a flux of extremely-high-energy (EHE), so-called cosmogenic, neutrinos is produced. The observation of these neutrinos with IceCube can probe the nature of UHECRs. We present a search for EHE neutrinos using 12.6 years of IceCube data. The non-observation of neutrinos with energies \gtrsim 10 PeV constrains the all-flavor neutrino flux at 1 EeV to be below E2 Φνe + νμ+ ντ ≃ 10-8 GeV cm-2 s-1 sr-1, the most stringent limit to date. This constrains the proton fraction in UHECRs of energy above 30 EeV to be \lesssim 70% if the evolution of the UHECR sources is similar to the star formation rate. Our analysis circumvents uncertainties associated with hadronic interaction models in studies of UHECR air showers, which also suggest a heavy composition at such energies.