Paper detail

Statistical Shapes of the Highest Pulses in Gamma--Ray Bursts

The statistical shapes of the highest pulse have been studied by aligned method. A wavelet package analysis technique and a developed pulse--finding algorithm have been applied to select the highest pulse from burst profiles observed by BATSE on board CGRO from 1991 April 21 to 1999 January 26. The results of this work show that the statistical shapes of the highest pulses are related to energy: the higher the energy, the narrower the pulse. However, the characteristic structures of the pulses have nothing to do with energy, which strongly supports the previous conclusion that the temporal profiles in different channels are self--similar. The characteristic structures of the pulses can be well described by a model proposed by Norris et al. (1996). The fitting parameters are: $t_r$=0.12, $t_d$=0.16, $\upsilon =1.09$, the ratio of $t_r$ to $t_d$ for the pulse is 0.75. The result leads to our conjecture that the mechanisms of bursts in different gamma-ray bands might be the same. The shock, either an internal or an external one, producing the pulse, might emit photons over the four energy channels in the same way.