Dependence of Temporal Properties on Energy in Long-Lag, Wide-Pulse Gamma-Ray Bursts

Abstract

Abstract We employed a sample by Norris et al. (2005, ApJ, 625, 324) to study the dependence of the pulse temporal properties on energy in long-lag, wide-pulse gamma-ray bursts. Our analysis shows that the pulse peak time, rise time scale, and decay time scale are power-law functions of energy, which is a preliminary report on the relationships between the three quantities and energy. The power-law indexes associated with the pulse width, rise time scale, and decay time scale are correlated, and the correlation between the indexes associated with the pulse width and the decay time scale is more obvious. In addition, we have found that the pulse peak lag is strongly correlated with the CCF lag, but the centroid lag is less correlated with the peak lag and the CCF lag. Based on these results and some previous investigations, we tend to believe that all energy-dependent pulse temporal properties may come from the joint contribution of both the hydrodynamic processes of the outflows and the curvature effect, where the energy-dependent spectral lag may be mainly dominated by the dynamic process, and the energy-dependent pulse width may be mainly determined by the curvature effect.