The time delay of gamma-ray bursts in the soft energy band.

Abstract

Using a cross correlation method, we find that there may exist gamma-ray bursts whose soft emission has a time delay relative to the high-energy emission. Autocorrelation was used to determine the duration of substructures in different energy bands of selected bursts,in order to examine the correlation between time def ay and broadening of soft emission. The results indicate a positive correlation with correlation coefficient 0.75 between the two parameters, this suggests that scattering could partly be the mechanism of time delay and broadening. The hardness ratios of the bursts with time delays are concentrated in a relatively narrow range.