Very high energy gamma rays from x-ray binary pulsars

A number of categories of celestial very high energy (>0.2 TeV) gamma ray sources have now been established. The most surprising discovery has been that one of the categories was X-ray binary sources containing pulsars. We describe the ground based atmospheric Cerenkov light techniques used to detect such very high energy gamma rays, and review the evidence for emission from X-ray binary pulsars. An attempt is made to establish patterns in the observed emissions as an aid to the understanding of the gamma ray production. Finally, the various models which have been put forward to explain the origin of these gamma rays are reviewed. (author)