Gamma-ray astrophysics - A new look at the universe

Gamma-ray astronomy, which may be defined to include the spectral region from above 100 keV to about 1000 GeV, permits investigation of the most energetic photons originating in the Galaxy and beyond. These observations provide the most direct means of studying the largest transfers of energy occurring in astrophysical processes, including the dynamic effects of the energetic charged cosmic-ray particles, element synthesis, and particle acceleration. Further, gamma-rays suffer negligible absorption or scattering as they travel in straight paths. Hence they may survive billions of years. Studies of the spatial, temporal, and energy distribution of cosmic gamma-rays will, therefore, provide fundamental new information for resolving some of the major problems in astrophysics today. Attention is given to the gamma-ray observations of the solar system, stellar objects, diffuse gamma-ray emission from the Galaxy, other galaxies and cosmology, and future prospects.