Neutrinos at High Energies: Disentangling Galactic and Extra-galactic components

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In 2013 the IceCube South Pole Neutrino Observatory has received the Physics World award for the Breakthrough of the Year for the first observations of high-energy cosmic neutrinos. The discovery, indeed, represents the birth of a new research field, the neutrino astronomy, that can definitively shed light on the sources of high-energy cosmic-rays and on the mechanisms through which they are produced. The origin of all of the detected neutrinos is still to be correctly identified. Just recently evidence for emission from the direction of the blazar TXS 0506+056 has been reported. The most important point to understand is if the neutrino events are all of extra-galactic origin or a galactic component is present, and which are the specific characteristics, like size of the acceleration region and magnetic field, of the possible sources. To achieve this goal a multi-messenger approach is necessary. In particular, it is important to compare the single point sources available in the current gamma-ray catalogues with the IceCube data, considering their spatial, timing and energy distribution. After identifying specific plausible candidates for the IceCube events, it is possible to consider the sensitivity of gamma-ray experiments, like the High-Altitude Water Cherenkov Observatory and the planned Cherenkov Telescope Array Project, to verify the origin of the IceCube events. For the final correct identification of the IceCube neutrinos, the detection of the events from different experiments will be fundamental. In this regard, the estimation of the prospects for ANTARES, for the possible extension of IceCube and for the planned cubic kilometre neutrino telescope in the Northern Hemisphere, KM3NeT, is mandatory.