Speaker
Description
The origin of very-high-energy Galactic cosmic-rays is currently hotly debated. Their most powerful sources in our Galaxy, also called “PeVatrons”, are expected to accelerate particles up to rigidities of at least a few PV, and possibly beyond. Such sources should also produce ultra-high-energy (UHE) gamma-rays. Recent observations by the LHAASO experiment with > 100 TeV gamma-rays show that several classes of sources may accelerate protons or electrons up to PeV energies, while casting doubts on the standard paradigm that most supernova remnants should be PeVatrons during their first few centuries.
In this talk, we will review the current status and the latest developments in the search for PeVatrons thanks to observations of UHE gamma-ray sources. In particular, LHAASO data demonstrates that some stellar clusters, microquasars and pulsar wind nebulae can accelerate particles beyond PeV energies. We will discuss possible acceleration mechanisms for these particles. Finally, we will also place further constraints on the nature of PeVatrons through a novel multi-messenger study, using the diffuse Galactic very-high-energy gamma-ray and neutrino emissions measured respectively by LHAASO and IceCube.