UHE Photons on the 'Knee' Pose Challenges to Dominant Model on Origins of Cosmic Rays

摘要

Once again,the Crab Nebula fell in spotlightwhen an international team working on thcLarge High-Altitude Air Shower Observatory(LHAASO),a large ground-based array for cosmic raycetection,identified it as a source of ultrahigh-energy(UHE)photons,or gamma-rays.Actually,the teamdiscovcred a total of 12 UHE photon sources,with themost energetic one crmitting photons at encrgies up to 1.4 petaclectronvolts(PeV,quadrillion or 10electronvolts),the highest ever detected by human beings.