X-RAY ECHOES FROM GAMMA-RAY BURSTS

The identification of an echo of reflected radiation in time histories of gamma-ray burst spectra can provide important information about the existence of binary companions or accretion disks in gamma-ray burst systems. Because of the nature of Compton scattering, the spectrum of the echo will be attenuated at gamma-ray energies compared with the spectrum of the primary burst emission. We describe the expected temporal and spectral signatures of the echo, our search for such echoes, and discuss implications for gamma-ray burst models.