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We first present recent developments in our theoretical understanding of particle acceleration to very high energies in the Galaxy. We find that proton acceleration to multi-PeV energies only occurs in a subset of supernova remnants, and earlier than usually assumed. The acceleration mechanism of TeV-PeV electrons in pulsar wind nebulae (PWNe) remains uncertain. We show with PIC simulations that electrons can be accelerated by the first-order Fermi process at the pulsar wind termination shock. We discuss the relevance of our findings to LHAASO.
Electrons eventually escape from old PWNe into the surrounding interstellar medium, and create extended >TeV gamma-ray emissions around them. Such "TeV halos" have been detected by HAWC around Geminga and Monogem. We demonstrate that the shapes of these halos can be used as probes of the interstellar turbulence, and we use HAWC measurements to place constraints on the turbulence properties around these two pulsars. We show how further constraints on cosmic-ray (CR) propagation on Galactic scales will be provided by LHAASO measurements of the diffuse Galactic gamma-ray emission.
Finally, we demonstrate that the shape of the CR anisotropy (at Earth) can be used as a new probe of the interstellar turbulence within a few tens of parsecs from Earth. The current CR data already rule out a range of turbulence models. The data of IceTop can be fitted either with a Goldreich-Sridhar model that contains a smooth deficit of parallel-propagating waves, or with isotropic fast agnetosonic waves.
Gwenael Giacinti studied at the Ecole Normale Superieure of Lyon (France), and earned his Ph.D. degree from Paris 7 University. From 2012 to 2015, he worked as a postdoctoral researcher at the University of Oxford (United Kingdom). He now works as a postdoctoral researcher at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg (Germany). He is interested in a number of topics in theoretical high-energy astrophysics and particle astrophysics, including cosmic-ray propagation, particle acceleration in pulsar wind nebulae, supernovae and supernova remnants, as well as gamma-ray astronomy. He is also interested in related plasma astrophysics problems, such as shock physics in the context of supernova shock breakout. He is the science working group coordinator of the Southern Wide field-of-view Gamma-ray Observatory (SWGO), and a member of the High Altitude Water Cherenkov (HAWC) Collaboration.
Video record is available: https://vshare.sjtu.edu.cn/open/305c4ea7161c75567b1a1be1dd5de5a2