Sub-TeV Gamma-Ray Astrophysics Using Large Air Čerenkov Telescopes

Abstract

In 1990’s Very High Energy Gamma-ray Astrophysics has dramatically advanced due to the advent of Imaging Air Cerenkov Telescopes (IACTs), and has been widely recognized as an important field of astronomy. After the first detection of persistent TeV gamma-ray emission from the Crab in 1989, several types of TeV gamma-ray sources have been detected and established. Successive discoveries of active galactic nuclei emitting TeV gamma rays after 1992 especially astonished and enabled us directly to watch the high energy phenomena around the huge black holes at the center of galaxies. Recent detections of TeV gamma-ray emission from several supernova remnants have been reported in both southern and northern skies, which had been eagerly looked forward to since the beginning of cosmic-ray physics. Those are expected to be a clue of not only the galactic cosmic-ray origin but also the understanding of the particle acceleration due to a diffusive shock. At first we present the recent observational results and the understanding of high energy phenomena in gamma-ray sources, particularly galactic TeV gamma-ray sources. A brief review of experimental aspect of Very High Energy Gamma-ray Astronomy are also described including the perspective of TeV gamma-ray astronomy in the next decade.