Search for Ultra-High-Energy Gamma-Rays from SN1987A

Abstract

We report here a search of data recorded by the Buckland Park air shower array from the first year after the supernova and set an upper limit to the proton luminosity of SN1987A of 7.7 × 1040 ergs s−1.

Ground-based Gamma-ray Astronomy

“…Again the periodic features of the sources (both pulsar and orbital modulation) are often used to search for signals amongst the cosmic ray background. The source 2A 1822-37.1 (Ciampa et al 1989 gives an indication of the statistical significance typical of UHE observations. This source was claimed by Ciampa et al (1989) with an overal 1 confidence level based on a search for periodic emission of 1.3% chance of error when statistical trials were taken into account.…”

“…The source 2A 1822-37.1 (Ciampa et al 1989 gives an indication of the statistical significance typical of UHE observations. This source was claimed by Ciampa et al (1989) with an overal 1 confidence level based on a search for periodic emission of 1.3% chance of error when statistical trials were taken into account. It was later observed by at higher energies with a probability of 2.5 x 10" 4 of the observation occurring by chance in the background distribution.…”

“…Gamma-ray showers are expected to be almost indistinguishable from conventional cosmic ray showers so that, to a first approximation, catalogues of cosmic ray showers will include any gamma-ray events occurring in the observation period. Since we would expect Galactic gamma-rays to come predominantly from the direction of the Milky Way, a search for excess events from the direction of the Milky Way will put limits on the level of gammaray production in the Galaxy (Bird et al 1989). This limit turns out to be of the order of the gamma-ray flux provided by one source of the intensity of Cyg X-3, and this is compatible with the overall level of cosmic ray production.…”

“…The cosmic ray sky is uniform at close to observational limits at all measured energies above those which exhibit heliospheric effects. Where measurements are most detailed, this means that deviations from uniformity are less than one part in one thousand (Bird and Clay 1989). So far as one can tell, the spectrum of cosmic ray energies ( Figure 1) is also almost featureless over a range of 10 11 times in energy (Gregory et al 1987).…”