GAMMA-RAY BURSTS: THE DEPENDENCE OF THE SPECTRAL LAG ON THE ENERGY

We investigated the dependence of a spectral lag against energy band based on 28 bright GRBs registered by SPI and IBIS/ISGRI of INTEGRAL observatory. It was found that for simple structure bursts or well separated pulses of multipulse bursts the spectral lag can be approximated by the relation of tau similar to Alg(E), where A is a positive parameter, which correlates with pulse duration. We have not found any negative lag in simple structure bursts or in well separated pulses. While investigating the time profile of the whole burst negative lag may appear due to different spectral parameters of the pulses.