Searches for Ultra-Ehigh-Energy Gamma Rays from Sn 1987A and Centaurus X-3

Searches for gamma rays above 100 TeV from SN 1987A and above 50 TeV from Cen X-3 were carried out with an air shower array at Mount Chacaltaya over a period of 3 years. The array, which consists of 13 4 m2 and 28 1 m2 scintillation detectors, was located on a slope of about 30i facing southward to e†ectively observe air showers coming from the directions of these sources. In the analysis, a selection by shower age parameter was applied to reduce the background due to showers initiated by protons or nuclei. No signi-cant excess of gamma rays (and/or neutral particles) from these sources was found; our upper limits on the Nux of gamma rays above 100 TeV from SN 1987A and above 50 TeV from Cen X-3 are 2.2 ) 10~13 and 3.5 ) 10~13 photons cm~2 s~1 (95% con-dence level), respectively. Subject headings: gamma rays: observations E stars: individual (Centaurus X-3) E supernovae: individual(SN 1987A)