PRISMA Colloquium

Thanks to their extremely weak interaction with matter and neutral electric charge, neutrinos travel vast cosmic distances without deflection, providing a unique and complementary approach to investigating the most energetic events in the Universe. Neutrino telescopes are designed to detect Cherenkov light inferred by neutrino interactions. After more than fifteen years of data collection, the pioneering ANTARES detector has been successfully dismantled, making way for its next-generation successor, KM3NeT, deployed at two sites in the Mediterranean Sea. Near the former ANTARES location, off the coast of Toulon (France), KM3NeT/ORCA is dedicated to studying the intrinsic properties of atmospheric neutrinos through their oscillations within the Earth. Further southeast, off the coast of Sicily, KM3NeT/ARCA is monitoring the high-energy sky in search of cosmic neutrinos. In this presentation, I will highlight the latest insights in neutrino (astro)physics emerging from the depths of the Mediterranean. Particular attention will be given to the recent detection of an ultra-high-energy neutrino event, designated KM3-230213A, by KM3NeT/ARCA. The observed particle is a muon with an estimated energy of 120+110−60 PeV. Its exceptionally high energy and nearly horizontal trajectory suggest that its parent neutrino originated from a cosmic accelerator or could potentially be the first detected cosmogenic neutrino—produced when ultra-high-energy cosmic rays interact with background photons in the Universe. This groundbreaking observation underscores the remarkable capabilities of deep-sea neutrino telescopes in unveiling new astrophysical phenomena. To also view graphic content, follow the link: https://www.thep.physik.uni-mainz.de/files/2025/04/Title_Abstract_Mainz_AK_16.04.2025.pdf