A flash of gamma rays that seem to originate from a random point in the sky; their most likely sources are believed to be supernova explosions of a very massive stars and mergers of neutron stars
Study of astronomical objects and phenomena that emit gamma rays. Gamma-ray telescopes are designed to observe high-energy astrophysical systems, including stellar coronas, white dwarf stars, neutron stars, black holes, supernova remnants, clusters of galaxies, and diffuse gamma-ray background radiation found along the plane of the Milky Way Galaxy. Because Earth's atmosphere blocks most gamma rays, observations are generally conducted by high-altitude balloons or spacecraft. In the 1960s defense satellites designed to detect X rays and gamma rays from clandestine nuclear testing serendipitously discovered enigmatic gamma-ray bursts coming from deep space. In the 1970s Earth-orbiting observatories found a number of gamma-ray point sources, including an exceptionally strong one, dubbed Geminga, that was later identified as a pulsar, the nearest yet detected. The Compton Gamma Ray Observatory, launched in 1991, mapped thousands of celestial gamma-ray sources; it also showed that the mysterious bursts are distributed across the sky, implying that their sources are at the distant reaches of the universe rather than in the Milky Way
Electromagnetic radiation emitted by radioactive decay and having energies in a range from ten thousand (10) electron volts. a beam of light with a short wavelength, that can pass through solid objects radi'ation. Penetrating very short-wavelength electromagnetic radiation, similar to an X ray but of higher energy, that is emitted spontaneously by some radioactive substances (see gamma decay, radioactivity). Gamma radiation also originates in the decay of certain subatomic particles, and in particle-antiparticle annihilation (See also antimatter). Gamma rays can initiate nuclear fission, can be absorbed by ejection of an electron (see photoelectric effect), and can be scattered by free electrons (see Compton effect)