HARD X-RAY AND GAMMA-RAYS FROM SUPERNOVAE

The hard electromagnetic radiation produced by and accompanying the explosion of supernovae is discussed. This radiation may have three origins: i) the eruption of the shock wave from the surface of the star; ii) radioactive decay of unstable isotopes produced during the explosion; and iii) gamma-rays produced by neutrino annihilation following accretion induced collapse. Though the latter has been proposed as a mechanism for making cosmological gamma-ray bursts, it is shown that this is unlikely.