Temporal properties of the short gamma-ray bursts

A temporal analysis has been performed on a sample of 100 bright gamma-ray bursts (GRBs) with T-90 < 2 s from the BATSE Current Catalog. The GRBs were denoised using a median filter and subjected to an automated pulse selecti on algorithm as an objective way of identifing the effects of neighbouring pulses. The rise times, fall times, FWHM, pulse amplitudes and areas were m easured and the frequency distributions are presented here. All are consist ent with lognormal distributions. The distribution of time intervals betwee n pulses is not random but consistent with a lognormal distribution. The ti me intervals between pulses and pulse amplitudes are highly correlated with each other. These results are in excellent agreement with a similar analys is that revealed lognormal distributions for pulse properties and correlate d time intervals between pulses in bright GRBs with T-90 > 2 s. The two sub -classes of GRBs appear to have the same emission mechanism which is probab ly caused by internal shocks. They may not have the same progenitors becaus e of the generic nature of the fireball model.