Abstract: On February 13, 2023, the KM3NeT telescope has detected a muon with an energy in the hundreds of petaelectronvolts. Given its energy and horizontal direction, it most probably originates from the interaction of an ultra-high-energy cosmic neutrino. This neutrino is the most energetic one detected so far, with an estimated energy of $220^{+570}_{-110}$ petaelectronvolts. This observation has triggered many follow-up studies, notably the search for an associated astrophysical source, constraints on cosmogenic models, the combination with IceCube and Auger non-observations at such energies, and implications for beyond-standard-model scenarii. After a general introduction on neutrino astronomy and Cherenkov neutrino telescopes, the seminar will cover the detection of this extraordinary event and the outcomes of the related studies, as well as the current status and future plans of the KM3NeT experiment.
Short bio: Mathieu Lamoureux is currently an FNRS postdoctoral researcher at UCLouvain (Belgium). He obtained his PhD at CEA Paris Saclay in 2018 on the search for hypothetical heavy neutrinos with the T2K experiment. In 2019, he was awarded a MSCA-COFUND fellowship at INFN Padova (Italy) and switched his focus towards neutrino astronomy. He also performed during a secondment period at UParis-Cité (France) in 2021. He has been working on the Super-Kamiokande and ANTARES experiments, with a focus on joint sources of neutrinos and gravitational waves and on neutrino emission from the Milky Way. At UCLouvain since 2022, he has been actively involved in the KM3NeT and IceCube Collaborations, pursuing the study of astrophysical neutrinos and their connections in the multimessenger picture.