Preprint
Search for Extremely-High-Energy Neutrinos and First Constraints on the Ultrahigh-Energy Cosmic-Ray Proton Fraction with IceCube
ArXiv.org
Cornell University
07/09/2025
DOI: 10.48550/arxiv.2502.01963
Abstract
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 E2Φνe+νμ+ντ ≃ 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 ≃ 30 EeV to be ≲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 ∼200 PeV KM3NeT neutrino candidate (KM3-230213A), finding it to be ∼ 2.9σ based on a joint-livetime fit between neutrino datasets.
Details
- Title: Subtitle
- Search for Extremely-High-Energy Neutrinos and First Constraints on the Ultrahigh-Energy Cosmic-Ray Proton Fraction with IceCube
- Creators
- R. Abbasi - Loyola University ChicagoM. Ackermann - Deutsches Elektronen-Synchrotron DESYJ. Adams - University of CanterburyS. K. Agarwalla - University of Wisconsin–MadisonJ. A. Aguilar - Université Libre de BruxellesM. Ahlers - University of CopenhagenJean-Marco Alameddine - TU Dortmund UniversityN. M. Amin - University of DelawareM HostertIceCube Collaboration
- Resource Type
- Preprint
- Publication Details
- ArXiv.org
- DOI
- 10.48550/arxiv.2502.01963
- ISSN
- 2331-8422
- Publisher
- Cornell University; Ithaca, New York
- Language
- English
- Date posted
- 07/09/2025
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984945909802771
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