Time variation of ultra high energy γ-ray from SN1987A

If the neutron star exists in the remnant of SN1987A, there is a possibility to check the acceleration activity of the pulsar in the very early phase. As indicated by the observation of Cyg X-3, the pulsar may generate a proton beam with energy up to 1017 eV, which interacts with the ejected matter and produces ultra high energy (UHE) γ-rays as well as UHE neutrinos with energy up to 1016 eV. Luminosity of UHE γ-rays will take a maximum at 5.5 months (8.3 months) from February 23rd, if the mass ejected by the supernova explosion with energy ∼ 1.4 x 1017 ergs/g is 7(solar mass)(15(solar mass)) and if the UHE protons are not confined in the ejecta by the turbulent magnetic fields. If they are completely trapped, the maximum epoch will be prolonged by the factor about 3. The proton beam luminosity will be limited to 7 x 1041 ergs/s at most if muons generated by the UHE neutrinos are not detected in the underground detectors. (author)