Revisiting the characteristics of the spectral lags in short gamma - ray bursts

In this paper, we restudy the spectral lag features of short bright gamma-ray bursts (T90 < 2.6s) with a BATSE time-tagged event (TTE) sample including 65 single pulse bursts. The cross-correlation technique is adopted to measure the lags between two different energy channels. Meanwhile, we also make an investigation of the characteristics of the ratios between the spectral lag and the full width at half maximum (FWHM) of the pulses, called relative spectral lags (RSLs). We conclude that spectral lags of short gamma ray bursts (SGRBs) are normally distributed and concentrated around the value of 0.014, with 40 percent of them having negative lags. With K-S tests, we find the lag distribution is identical with a normal one caused by white noises, which indicates the lags of the vast majority of SGRBs are so small that they are negligible or nonmeasurable, as Norris & Bonnell have suggested.