Very-high-energy gamma-ray telescopes

Abstract

Telescopes capable of collecting the highest energy light, called gammaradiation, explore a region of the electromagnetic spectrum that was largelyinaccessible until recently. Observations at the highest energies reveal theexistence and properties of extreme sites in the Universe. In this chapter, I cover the techniques used to detect photons at frequencies above 10 23 Hz, photonenergy > 100 MeV, in the so-called pair production regime. Telescopes employing particle and optical detection methods are used in space or the upper atmosphere as well as on the ground. Gamma-ray astrophysics is a young field with only one or two generations of instruments completed for each of several techniques. In the past decade, telescopes throughout this band have generated significantly deeper andmore complete surveys and catalogs of the high- and very-high-energysky. Already the results are spectacular, but many challenges remain forenhancing the performance of high- and very-high-energy gamma-raytelescopes.