The Tibet air shower array at an altitude of 4300 m (above sea level) has been in operation since January 1990. We have searched for continual emission of 10-TeV gamma rays from the Crab Nebula, Cygnus X-3, and Hercules X-1 during the period from June 1990 through January 1992. No dc excess is found from these three sources. Flux upper limits above 10 TeV are obtained to be 1.2×10-12 cm-2s-1 for the Crab Nebula, 1.1×10-12 cm-2s-1 for Cygnus X-3, and 0.58×10-12 cm-2s-1 for Hercules X-1 at the 95% C.L. This is the first observation, with an air shower array, for these sources in the 10-TeV energy region.
|ジャーナル||Physical Review Letters|
|出版ステータス||Published - 1992 10月 26|
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