A search for ehanced ultra-high-energy gamma-ray emission from Crab Nabula using LHAASO-KM2A data

The Crab Nebula is an important object of study in gamma-ray astronomy. Since the full array operation of LHAASO-KM2A in July 2021, it has conducted long-term and efficient observations of the Crab Nebula in ∼10 TeV energy range. We have obtained light curves, spectrum and ultra-high-energy photon( >100 TeV) data from the direction of the Crab Nebula since the full array operation of KM2A. The Crab Nebula exhibits flaring phenomena in the hundreds of MeV to GeV range, firstly detected by the AGILE satellite of the Italian Space Agency, and later detected multiple times by NASA’s Fermi-LAT. Previous observations of these flares by VERITAS and HESS Cherenkov telescopes were made in coordination with Fermi, but no significant flux variation was found in their energy ranges. In our analysis of the long-term light curves from Fermi since the full array operation of KM2A, we detected a significant flares in December 2023. During these corresponding time periods, we studied the light curves and spectrum from KM2A and found no significant flux variations, only providing upper limits on the flux variation.