Speaker
Description
In 2021, the Tibet ASγ experiment achieved the first detection of Galactic diffuse gamma rays at Sub-PeV energies (E > 100 TeV = 10^14 eV), ensuring the presence of PeVatrons in the Galaxy. On the other hand, in 2024, the LHAASO observatory claimed the detection of 43 Sub-PeV gamma-ray sources with one- order-of-magnitude better sensitivity than other sub-PeV gamma-ray observatories. To discuss the origin of the Tibet diffuse events and the interpretation, it is important to check the overlap between these diffuse events and the locations of the LHAASO sub-PeV gamma-ray sources. Surprisingly, none of the 23 Tibet diffuse gamma-ray events above 398 TeV originate from the LHAASO sub-PeV gamma-ray sources. This supports the insight that the Tibet diffuse events above 398 TeV are indeed generated by cosmic-ray nuclei wandering within the Galaxy. The result not only strongly supports the existence of PeVatrons in the Galaxy capable of accelerating cosmic-ray protons to PeV energies but also provides important insights into the propagation of cosmic rays within the Galaxy. This presentation will discuss in detail the aforementioned discovery and its implications.
