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 (T-90 < 2.6 s) with a BATSE time-tagged event 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 of the pulses, called relative spectral lags. We conclude that spectral lags of short gamma-ray bursts (SGRBs) are normally distributed and concentrated around the value of 0.014, with 40 per cent of them having negative lags. With Kolmogorov-Smirnov tests, we find that the lag distribution is identical to a normal one caused by white noises, which indicates that the lags of the vast majority of SGRBs are so small that they are negligible or non-measurable, as Norris & Bonnell have suggested.

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