Analysis of temporal features of gamma-ray bursts in the internal shock model

In a recent paper we calculated the power density spectrum of gamma-ray bursts arising from multiple shocks in a relativistic Rind. The wind optical thickness is one of the factors to which the power spectrum is most sensitive; therefore, we have further developed our model by taking into account the photon downscattering on the cold electrons in the wind. For an almost optically thick wind we identify a combination of ejection features and wind parameters that yield bursts with an average power spectrum in agreement with observations and with an efficiency of converting the wind kinetic energy in 50-300 keV emission of order 1%. For the same set of model features, the interval time between peaks and the pulse fluence have distributions consistent with the lognormal distribution observed in real bursts.