gamma-ray transientsSources of transient gamma-ray outbursts, the vast majority of which lie within 10° of the galactic plane and have peak luminosities of 1029 to about 1028 joules per second. Both neutron star and black-hole systems exhibit such outbursts. The γ-ray emission features of black-hole candidates are particularly spectacular and may prove to be a collective signature of the presence of a black-hole system. They include hard (E ≥ 200 keV) power-law emission tails, rapid stochastic flickering, broad electron-positron pair plasmalike spectral features; broadened and redshifted 511 keV line features; the presence of Compton backscattered spectral features near 170 keV.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006