Searches for high-energy cosmic neutrinos from the Deep-Mediterranean Sea

by Prof. Antoine Kouchner (Université Paris Cité)

Tuesday 13 May 2025, 15:00 → 17:00 Europe/Berlin

Due to their weak interaction with matter and neutral electrical charge, neutrinos traverse cosmic distances without deflection, offering an interesting and complementary alternative way to probe into the most energetic events in the Universe.

Neutrino telescopes are designed to capture the Cherenkov light induced by neutrino interactions. After more than a decade and a half of data taking, the pioneering ANTARES has been successfully dismantled to leave the floor to the next-generation detector KM3NeT, deployed on two sites the Mediterranean Sea. Close the former location of ANTARES, offshore Toulon (France), KM3NeT/ORCA is designed to infer intrinsic properties of atmospheric neutrinos through their oscillation in the Earth. At the south-east of Sicily, KM3NeT/ARCA has started to monitor the high energy sky search for cosmic neutrinos.

In this presentation, I will discuss the latest insights in neutrino (astro)physics emerging from the depths of the Mediterranean. A particular focus will be on 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 observed 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 uncovering new astrophysical phenomena.