Neutrino Follow-Up Analysis of GRB 221009A with KM3NeT

Instituto de Física Corpuscular (CSIC-UV). Parque Científico, C/ Catedrático José Beltrán, 2. 46980 Paterna, Valencia. Spain

^* e-mail: Juan.Palacios@ific.uv.es

Published online: 6 March 2025

Abstract

Gamma-ray bursts are powerful explosions emitting high-energy photons, followed by a less energetic afterglow emission. They occur at a rate of a few per day in the observable Universe. After more than fifty years of detection and characterisation in the electromagnetic spectrum, they are considered potential sources of extragalactic cosmic rays. Despite no neutrinos have been detected so far in coincidence with these violent phenomena, numerous models predict neutrino emissions by different mechanisms.

On October 9th, 2022, several experiments, including the Swift and the Fermi satellites, detected an extraordinarily bright burst, referred to as GRB 221009A, for which the LHAASO observatory reported photons detection up to ∼10 TeV. This energetic transient event presented an exceptional opportunity for the search for neutrinos in temporal and spatial coincidence.

The KM3NeT undersea neutrino infrastructure was operating with 21 lines of the ARCA telescope and 10 lines of the ORCA detector at the time of this event, allowing for a real-time search for neutrinos from GRB 221009A. A refined study including data reprocessing and systematics effects was conducted covering multiple time windows in a wide energy range, from MeV up to a few PeVs. This contribution summarises the main results of the analyses, focusing on how KM3NeT performs the follow-up of gamma-ray bursts in a multi-messenger context.