Neutrino Triggered Target of Opportunity: multi-messenger view of the gamma-ray flaring blazar OP313

In the last decades, the field of astrophysics has increasingly embraced a multi-messenger approach, particularly in investigating extragalactic phenomena like Active Galactic Nuclei (AGNs) and more specifically the sub-class of blazars. A notable event in 2017, involving the detection of a high-energy neutrino from the blazar TXS 0506+056 alongside a gamma-ray flare observed by MAGIC telescopes, underscored the importance of this approach. This thesis focuses on another blazar, OP 313, which experienced a significant high energy flare from December 2023. This event provided an opportunity for a comprehensive multi-messenger view, especially since recent neutrino alerts originated from the same source direction. The thesis aims to identify potential correlations between gamma photons observed by MAGIC and Fermi-LAT telescopes and neutrino signals from IceCube. Methodologically, data from MAGIC telescopes are calibrated and converted, followed by background cleaning and image parameterization. Specific algorithms are employed to derive information about the primary particle’s type, direction, and energy, leading to a high-level analysis to determine the significance of the flare, spectral energy distribution, and light curve. The results indicate a strong emission of Very High Energy (VHE) gamma rays from OP 313, a phenomenon previously undetected. Fermi-LAT observations also show intense emission persisting from November 2023. Additionally, two recent neutrino alerts from IceCube were reported in the direction of OP 313, just above the detection threshold. The study of OP 313, alongside blazars in general, holds significance in elucidating the mechanisms within blazar’s jets. A multi-messenger approach is deemed essential for discerning whether the Cosmic Ray (CR) acceleration scenario is lepto-hadronic or purely leptonic.