A template for describing intrinsic GRB pulse shapes

A preliminary study of a set of well-isolated pulses in GRB light curves indicates that simple pulse models, with smooth and monotonic pulse rise and decay regions, are inadequate. Examining the residuals of fits of pulses to such models suggests the following patterns of departure from the smooth pulse model of Norris et al. (2005): A Precursor Shelf occurs prior to or concurrent with the exponential Rapid Rise. The pulse reaches maximum intensity at the Peak Plateau, then undergoes a Rapid Decay. The decay changes into an Extended Tail. Pulses are almost universally characterized by hard-to-soft evolution, arguing that the new pulse features reflect a single physical phenomenon, rather than artifacts of pulse overlap.