Highlights from the IceCube Neutrino Observatory

TL;DR

The paper surveys the IceCube Neutrino Observatory's milestones in high-energy neutrino astronomy, including the first diffuse astrophysical neutrino flux, the identification of NGC 1068 as a neutrino source, and the Milky Way detection, framing these results within a multimessenger context. It reviews the detector's capabilities and signatures, highlights recent evidence for spectral structure and flavor composition consistent with pion production, and discusses constraints on cosmogenic neutrinos and dark-matter scenarios. The authors then outline a concrete plan for the next generation—IceCube Upgrade and IceCube-Gen2—to extend energy reach, improve reconstruction and calibration, and add radio detection, promising substantial gains in source sensitivity, flavor physics, and ultra-high-energy neutrino science. Collectively, these developments position IceCube to deepen our understanding of cosmic-ray origins, test new physics, and advance multi-messenger astronomy across a broad energy range.

Abstract

The IceCube neutrino observatory has been successfully operating in its full configuration for almost 15 years and is characterized by a remarkably high stability and uptime. During this time, it has made many groundbreaking observations, such as the first detection of a high-energy diffuse cosmic neutrino flux or, more recently, the identification of the AGN NGC1068 as a steady source of high-energy neutrino emission and the observation of neutrinos from the Milky Way. In this talk, new developments in these areas will be discussed and further highlights presented. The second part then looks at the ongoing developments at the South Pole with IceCube Upgrade and IceCube-Gen2 and discusses their potential for advancing neutrino and astroparticle physics.

Figures (10)

• Figure 1: Measured diffuse neutrino spectrum per neutrino flavor as a function of energy. The different components shown are: Unfolded total muon neutrino flux (green circles Rootselar:2025icrc); Measured cosmic neutrino flux (black circles IceCube:2025tgp); 90% U.L. on EHE neutrino above $2\,\mathrm{PeV}$ (IceCubeCollaborationSS:2025jbi). Also shown are the 68% uncertainty bands for two analyses with different event selections (ESTES: blue IceCube:2024fxo; MESE: red IceCube:2025tgp) and the measured flux at the Glashow resonance IceCube:2021rpz.
• Figure 2: Left: Measured diffuse astrophysical muon neutrino spectrum together with previous best fit results of a simple power law for different event samples (for details see Basu:2025icrc). Right: Fit of different spectrum hypotheses: Broken Power-law (BPL), Simple Power-Law (SPL) with bump, Log-parabola, SPL with cutoff and SPL. Both plots taken from Basu:2025icrc.
• Figure 3: Neutrino flavor triangle for the measured diffuse neutrino flux at Earth assuming full mixing. The best fit assumes a broken power-law. Taken from Balagopal:2025icrc.
• Figure 4: Left: IceCube upper limit on the cosmogenic neutrino flux as a function of energy together with the Auger upper limit and model predictions. Also shown is the flux derived from the KM3NeT event. For details and references see Meier:2025icrc. Right: Proton fraction of ultra-high energy cosmic rays as a function of the source evolution parameter for two source evolution models. See Meier:2025icrc for more details. Both plots taken from Meier:2025icrc.
• Figure 5: Combined reconstructed hydrogen and helium flux. Systematic uncertainties are represented by brackets while error bars describe statistical uncertainty and energy resolution. For details refer to Saffer:2025icrc.