A search for extremely-high-energy neutrinos with IceCube and implications for the ultra-high-energy cosmic-ray proton fraction

Icecube Collaboration

doi:10.22323/1.501.1122

A search for extremely-high-energy neutrinos with IceCube and implications for the ultra-high-energy cosmic-ray proton fraction

Icecube Collaboration

Physics and Astronomy

University of Delaware
RWTH Aachen University
Karlsruhe Institute of Technology
Adelaide University
Loyola University Chicago
German Electron Synchrotron
University of Canterbury
University of Wisconsin-Madison
Université libre de Bruxelles
University of Copenhagen
TU Dortmund University
University of Kansas
Marquette University
Harvard University
University of Utah
Michigan State University
South Dakota School of Mines & Technology
University of California at Irvine
Technical University of Munich
University of California at Berkeley
Ohio State University
Ruhr University Bochum
Uppsala University
University of Rochester
University of Maryland, College Park
University of Padua
University of Alabama
Johannes Gutenberg University Mainz
Georgia Institute of Technology
Queen's University Kingston

Research output: Contribution to journal › Conference article › peer-review

Abstract

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 ≳ 10 PeV constrains the all-flavor neutrino flux at 1 EeV to be below E²Φ_{νe+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 ≲ 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.

Original language	English
Article number	1122
Journal	Proceedings of Science
Volume	501
DOIs	https://doi.org/10.22323/1.501.1122
State	Published - Dec 30 2025
Event	39th International Cosmic Ray Conference, ICRC 2025 - Geneva, Switzerland Duration: Jul 15 2025 → Jul 24 2025

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@article{586df74676214e7ebd98d704495315b1,

title = "A search for extremely-high-energy neutrinos with IceCube and implications for the ultra-high-energy cosmic-ray proton fraction",

abstract = "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 ≳ 10 PeV constrains the all-flavor neutrino flux at 1 EeV to be below E2Φνe+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 ≲ 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.",

author = "\{Icecube Collaboration\} and Schroeder, \{Frank G.\} and Federico Bontempo and R. Abbasi and M. Ackermann and J. Adams and Agarwalla, \{S. K.\} and Aguilar, \{J. A.\} and M. Ahlers and Alameddine, \{J. M.\} and S. Ali and Amin, \{N. M.\} and K. Andeen and C. Arg{\"u}elles and Y. Ashida and S. Athanasiadou and Axani, \{S. N.\} and R. Babu and X. Bai and J. Baines-Holmes and A. Balagopal and Barwick, \{S. W.\} and S. Bash and V. Basu and R. Bay and Beatty, \{J. J.\} and Tjus, \{J. Becker\} and P. Behrens and J. Beise and C. Bellenghi and B. Benkel and S. BenZvi and D. Berley and E. Bernardini and Besson, \{D. Z.\} and E. Blaufuss and L. Bloom and S. Blot and I. Bodo and F. Bontempo and Motzkin, \{J. Y.Book\} and Meneguolo, \{C. Boscolo\} and S. B{\"o}ser and O. Botner and J. B{\"o}ttcher and J. Braun and B. Brinson and Z. Brisson-Tsavoussis and Burley, \{R. T.\} and D. Butterfield and J. Kiryluk",

note = "Publisher Copyright: {\textcopyright} Copyright owned by the author(s); 39th International Cosmic Ray Conference, ICRC 2025 ; Conference date: 15-07-2025 Through 24-07-2025",

year = "2025",

month = dec,

day = "30",

doi = "10.22323/1.501.1122",

language = "English",

volume = "501",

journal = "Proceedings of Science",

issn = "1824-8039",

}

TY - JOUR

T1 - A search for extremely-high-energy neutrinos with IceCube and implications for the ultra-high-energy cosmic-ray proton fraction

AU - Icecube Collaboration

AU - Schroeder, Frank G.

AU - Bontempo, Federico

AU - Abbasi, R.

AU - Ackermann, M.

AU - Adams, J.

AU - Agarwalla, S. K.

AU - Aguilar, J. A.

AU - Ahlers, M.

AU - Alameddine, J. M.

AU - Ali, S.

AU - Amin, N. M.

AU - Andeen, K.

AU - Argüelles, C.

AU - Ashida, Y.

AU - Athanasiadou, S.

AU - Axani, S. N.

AU - Babu, R.

AU - Bai, X.

AU - Baines-Holmes, J.

AU - Balagopal, A.

AU - Barwick, S. W.

AU - Bash, S.

AU - Basu, V.

AU - Bay, R.

AU - Beatty, J. J.

AU - Tjus, J. Becker

AU - Behrens, P.

AU - Beise, J.

AU - Bellenghi, C.

AU - Benkel, B.

AU - BenZvi, S.

AU - Berley, D.

AU - Bernardini, E.

AU - Besson, D. Z.

AU - Blaufuss, E.

AU - Bloom, L.

AU - Blot, S.

AU - Bodo, I.

AU - Bontempo, F.

AU - Motzkin, J. Y.Book

AU - Meneguolo, C. Boscolo

AU - Böser, S.

AU - Botner, O.

AU - Böttcher, J.

AU - Braun, J.

AU - Brinson, B.

AU - Brisson-Tsavoussis, Z.

AU - Burley, R. T.

AU - Butterfield, D.

AU - Kiryluk, J.

PY - 2025/12/30

Y1 - 2025/12/30

N2 - 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 ≳ 10 PeV constrains the all-flavor neutrino flux at 1 EeV to be below E2Φνe+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 ≲ 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.

AB - 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 ≳ 10 PeV constrains the all-flavor neutrino flux at 1 EeV to be below E2Φνe+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 ≲ 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.

UR - https://www.scopus.com/pages/publications/105029059415

U2 - 10.22323/1.501.1122

DO - 10.22323/1.501.1122

M3 - Conference article

AN - SCOPUS:105029059415

SN - 1824-8039

VL - 501

JO - Proceedings of Science

JF - Proceedings of Science

M1 - 1122

T2 - 39th International Cosmic Ray Conference, ICRC 2025

Y2 - 15 July 2025 through 24 July 2025

ER -

A search for extremely-high-energy neutrinos with IceCube and implications for the ultra-high-energy cosmic-ray proton fraction

Abstract

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