The UHE neutrino KM3-230213A

The UHE neutrino KM3-230213A XXI Workshop on Neutrino Telescopes Padova, September 29th – October 3rd 2025 Luigi Antonio Fusco [email protected] Universit`a degli Studi di Salerno, INFN-NA Gruppo collegato di Salerno Outline 1. The KM3NeT detectors 2. The event 3. The global landscape The UHE neutrino KM3-230213A 2/25 The KM3NeT detectors Underwater neutrino telescope in the Mediterranean Sea •KM3NeT/ARCA: neutrino astronomy •KM3NeT/ORCA: neutrino oscillations •Same collaboration, same technology For more details on KM3NeT, check out the talks in the parallel and plenary sessions The UHE neutrino KM3-230213A 3/25 The KM3NeT technology The UHE neutrino KM3-230213A 4/25 Current status ARCA-51 footprint ORCA-28 footprint The UHE neutrino KM3-230213A 5/25 KM3-230213A1 1S.Aiello et al. [KM3NeT], Nature 638: 376-382 (2025) The UHE neutrino KM3-230213A 6/25 The UHE neutrino KM3-230213A 7/25 First observation •A track-like event •Brightestaamong 108events collected in the 21-line ARCA configuration •Very horizontal •Extremely high-quality reconstruction aIn terms of number of triggered PMTs. Also, highest-energy event from likelihood reconstruction The UHE neutrino KM3-230213A 8/25 The UHE neutrino KM3-230213A 9/25 The neutrino flux •Considering the central 90% E−2energy range [72 PeV-2.6 EeV] •Assuming a steady isotropic flux •Assuming E−2over this energy range ⇒E2Φ(E) = 5.8+10.1 −3.7×10−8GeV (cm2s sr)−1 produces 1 event in the considered data •Uncertainties according to Feldman&Cousins The UHE neutrino KM3-230213A 16/25 KM3NeT alone S.Aiello et al. [KM3NeT], Nature 638: 376-382 (2025) The UHE neutrino KM3-230213A 17/25 KM3NeT + IceCube + Auger O.Adriani et al. [KM3NeT], PRX 15: 031016 (2025) The UHE neutrino KM3-230213A 18/25 Cosmogenic origin •Investigated a cosmogenic origin •Different source evolution •Different zmax •Also: subdominant p population in UHECR would boost the neutrino flux at the EeV scale O.Adriani et al. [KM3NeT], APJ 984: L41 (2025) The UHE neutrino KM3-230213A 19/25 Is there anything in that direction? The UHE neutrino KM3-230213A 20/25 (not) Galactic origin O.Adriani et al. [KM3NeT], arXiv:2502.08387 The UHE neutrino KM3-230213A 21/25 Blazars O.Adriani et al. [KM3NeT], arXiv:2502.08484 The UHE neutrino KM3-230213A 22/25 Blazars •No conclusive statement given the large R(99%) •Major radio flare from PMN J0606-0724 •Gamma-ray flare for the source 0605-085 •X-ray activity for MRC 0614-083 The UHE neutrino KM3-230213A 23/25 What’s next •Diffuse flux from transients (GRB1, blazars) also investigated •Beyond Standard Model options (e.g. heavy Dark Matter, Primordial Black Hole evaporation) and study on Lorentz Invariance Violation2 •Broader extremely-high-energy searches, also joining with IceCube and Auger •Updates on the event properties: new detector calibration, energy estimation, tau origin Huge resonance from both the experimental (many further followups from multimessenger observatories) and theoretical/phenomenological point of view 1O.Adriani et al. [KM3NeT], arXiv:2509.14895 2O.Adriani et al. [KM3NeT], arXiv:2502.12070, in publication on Communication Physics The UHE neutrino KM3-230213A 24/25 KM3NeT@Neutel •L.A. Fusco, Observation of the ultra-high-energy neutrino event KM3-230213A, Tue afternoon •R. Muller, Search for cosmic neutrino sources with two years of KM3NeT/ARCA data, Tue afternoon •R. Clark, Dynamic positioning and orientation calibrations of the KM3NeT/ORCA detector, Wed morning •F. Benfenati Gualandi, The data acquisition system for Phase-2 of the KM3NeT/ARCA neutrino telescope, Wed morning •I. Rea, The KM3NeT Digital Optical Module: a multi-PMT approach, Thu morning •M. Benhassi, Prospects of neutrino observations of the Central Molecular Zone and Cygnus Cocoon, Thu morning •A. Lazo Pedrajas, Status and results of the KM3NeT/ORCA experiment, Thu afternoon •A. Marinelli, Status and results of the KM3NeT/ARCA experiment, Fri morning The UHE neutrino KM3-230213A 25/25