Detection of TeV gamma rays from Mrk 501 at high flaring state of activity in 1997 with the Tibet air shower array

Amenomori, M.; Ayabe, S.; Cao, P. Y.; Ding, L. K.; Fen, Z. Y.; Fu, Y.; Guo, H. W.; He, M.; Hibino, K.; Hotta, N.; Huang, Q.; Huo, A. X.; Izu, K.; Jia, H. Y.; Kajino, F.; Kasahara, K.; Katayose, Y.; Li, J. Y.; Lu, H.; Lu, S.L.
June 2000
AIP Conference Proceedings;2000, Vol. 515 Issue 1, p139
Academic Journal
The BL Lac object Mrk 501 came into a high flaring state in 1997, brightest in the sky at TeV energies. Using the air shower data obtained with a high density part of the Tibet II array, being operating at Yangbajing since 1996, we searched for γ-ray signals from this source during the period from February to August in 1997. The result shows a 3.7σ excess for showers with its mode energy 3 TeV for the whole period and 4.7σ excess for the period from April 7 to June 16. The estimated energy spectrum of γ rays is consistent with those obtained by imaging atmospheric Cherenkov detectors. © 2000 American Institute of Physics.


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