Speaker
Description
The origin of astrophysical neutrinos at hundreds of TeV is still an open issue and an important step towards the understanding of the origin of cosmic rays. In this context, the real-time follow-up of neutrino events is a promising approach for the identification of the emitting objects. The imaging atmospheric Cherenkov telescopes (IACTs) – FACT, H.E.S.S., MAGIC and VERITAS – play a relevant role in the search of very high energy (VHE, >100 GeV) gamma-ray counterparts. This is achieved through active follow-up program of target-of-opportunity observations of neutrino alerts sent by IceCube. This program has two main components: the follow-up of single high-energy neutrino candidate events of potential astrophysical origin, and the observation of known gamma-ray sources around which a spatial and temporal cluster of candidate neutrino events has been identified by IceCube. Thanks to this approach, in 2017, a link was established between the flaring gamma-ray blazar TXS 0506+056 and the high energy neutrino event IC-170922A detected by IceCube, providing compelling evidence for an electromagnetic counterpart of a neutrino event. The detection by MAGIC of VHE gamma rays from this source helped to establish the association and constrained the modeling of the blazar emission at the time of the IceCube event.
In this joint contribution of FACT, H.E.S.S., MAGIC, VERITAS, and IceCube, we present an overview of recent results from the IACTs follow-up program of IceCube neutrino alerts, highlighting the most interesting observations.
| Collaboration | IceCube, FACT, H.E.S.S., MAGIC, VERITAS |
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