Speaker
Description
The Large High Altitude Air Shower Observatory (LHAASO) has previously reported a catalog of gamma-ray sources above 25 TeV, revealing a population of very-high-energy emitters in the Galactic plane. Identifying sources that remain detectable beyond 400 TeV is crucial for pinpointing the most extreme Galactic particle accelerators (PeVatrons). At these energies, the implied parent particles likely reach the multi-PeV range, close to the knee of the cosmic-ray spectrum. In this work, we perform a blind search for gamma-ray sources in the Galactic disk using LHAASO-KM2A data with an energy threshold of 400 TeV. We detect five sources with statistical significance exceeding 5σ. All are positionally consistent with previously reported LHAASO sources above 25 TeV. They are independently detected here at higher energies. This provides an independent confirmation that their gamma-ray emission extends into the ultra-high-energy regime above 400 TeV. These sources are therefore promising PeVatron candidates, meeting a key observational signature expected from sources that may accelerate cosmic rays to the knee, and provide prioritized targets for multi-messenger observations, particularly searches for high-energy neutrinos. Our results demonstrate that LHAASO can effectively probe the ultra-high-energy sky and isolate the most extreme Galactic accelerators.
