Very-high-energy gamma rays and neutrinos: The search for PeVatrons

Since its discovery more than one hundred years ago, the origin of the cosmic-ray flux measured on Earth is still unknown: in order to explain the energy region below the knee, supernova remnants are usually addressed, even though no clear indication of PeV energies has been observed so far in such a kind of sources. However, recently, the Galactic Center region has been detected as a multi-TeV gamma-ray emitter: in the case of hadronic origin of the radiation, this would imply the existence of PeV primary protons. Hence, this detection triggers the search for a PeVatron at the center of our Galaxy. In order to identify the origin of the emission, a multi-messenger strategy appears suitable: in fact, in the hadronic scenario, neutrinos would constitute a natural counterpart of the electromagnetic emission. The fundamental role of neutrinos in disentangling the origin of the observed gamma rays is here discussed.