Search for Multi-TeV gamma-ray emission from nearby SNRs with the Tibet air shower array The Tibet ASγ Collaboration

The Tibet air-shower array operating at Yangbajing (4300 m above sea level) is sensitive to gamma-ray air showers at energies as low as 3 TeV. The observation of the Moon’s shadow has provided a direct check of the angular resolution, the energy estimation and the systematic pointing error of this air-shower array. Using these data, we have searched for multi-TeV gamma-ray emission from 27 SNRs located within 10 kpc distance in the declination band of −10° to +70°. The signal from the Crab Nebula was detected at 5.5 σ level. The intensity observed is (4.61±0.90)×10−12 cm−2 s−1 TeV−1 at 3 TeV. No significant DC excess was found from any of these SNRs except from the Crab Nebula.