Search for Extremely-High-Energy Neutrinos and First Constraints on the Ultrahigh-Energy Cosmic-Ray Proton Fraction with IceCube
PHYSICAL REVIEW LETTERS, cilt.135, sa.3, 2025 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 135 Sayı: 3
- Basım Tarihi: 2025
- Doi Numarası: 10.1103/physrevlett.135.031001
- Dergi Adı: PHYSICAL REVIEW LETTERS
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, INSPEC, MathSciNet, zbMATH, DIALNET, Nature Index
- Orta Doğu Teknik Üniversitesi Adresli: Hayır
Özet
We present a search for the diffuse extremely-high-energy neutrino flux using 12.6 years of IceCube data. The nonobservation of neutrinos with energies well above 10 PeV constrains the all-flavor neutrino flux at 1018 eV to a level of E-2 Phi(nu e + nu mu + nu tau) similar or equal to 10(-8) GeV cm(-2) s(-1) sr(-1), the most stringent limit to date. Using these data, we constrain the proton fraction of ultrahigh-energy cosmic rays (UHECRs) above similar or equal to 30 EeV to be less than or similar to 70% (at 90% CL) if the cosmological evolution of the sources is comparable to or stronger than the star formation rate. This is the first result to disfavor the "proton-only" hypothesis for UHECR in this evolution regime using neutrino data. This result complements direct air-shower measurements by being insensitive to uncertainties associated with hadronic interaction models. We also evaluate the tension between IceCube's nonobservation and the similar to 200 PeV KM3NeT neutrino candidate (KM3-230213A), finding it to be similar to 2.9 sigma based on a joint-livetime fit between neutrino datasets.