New insights into the most extreme particle accelerators in our Galaxy: Where are the PeVatrons?

The origin of very-high-energy Galactic cosmic-rays is currently under strong debate. 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. 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 particular, LHAASO
data demonstrates that some stellar clusters, microquasars and pulsar wind nebulae can accelerate particles
Beyond PeV energies. In this talk, we will discuss the latest developments in the search for PeVatrons,
and discuss in detail 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.