Gamma Ray Astronomy with Muons Typeset Using Revt E X

Although gamma ray showers are muon-poor, they still produce a number of muons suucient to make the sources observed by GeV and TeV telescopes observable also in muons. For sources with hard gamma ray spectra there is a relativèenhancement' of muons from gamma ray primaries as compared to that from nucleon primaries. All shower gamma rays above the photo-production threshold contribute to the number of muons N , which is thus proportional to the primary gamma ray energy. With gamma ray energy 50 times higher than the muon energy and a probability of muon production by the gammas of about 1%, muon detectors can match the detection ee-ciency of a GeV satellite detector if their eeective area is larger by 10 4. The muons must have enough energy for suuciently accurate reconstruction of their direction for doing astronomy. These conditions are satissed by relatively shallow neutrino detectors such as AMANDA and Lake Baikal and by gamma ray detectors like MILAGRO. TeV muons from gamma ray primaries, on the other hand, are rare because they are only produced by higher energy gamma rays whose ux is suppressed by the decreasing ux at the source and by absorption on interstellar light. We show that there is a window of opportunity for muon astronomy with the AMANDA, Lake Baikal and MILAGRO detectors.