The ambiguous nature of cosmic ray PeVatrons

About

Understanding which are the Galactic sources responsible for the production of the highest energy cosmic rays is one of the main task of the High Energy Astrophysics. This long standing problem has recently received new lymph thanks to the results obtained from ground-based high energy gamma-ray detectors like HAWC and LHAASO. Those experiments have shown that the Galaxy is full of PeVatrons, namely sources able to produce particles up the impressive energy of Peta electronvolts. Probably the most impressive result is that, contrary to past expectations, different type of sources seem to work as PeVatrons, like pulsar wind nebulae, supernova remnants, stellar clusters and micro quasars. However, at the moment, it is unclear if the knee region of the CR spectrum is dominated by a single type of sources or is rather the convolution of several different classes. Moreover, the pour angular resolution of the mentioned detectors often prevent one to precisely identify the source nature. In this talk I will review the present status of the field.