Profiles of γ-ray bursts and their component pulses

One physically informative regularity of the otherwise heterogenous γ-ray bursts, is that many consist of well defined pulses. To objectively quantify burst temporal structures, we developed an automatic modeling procedure for time-tagged event (TTE) and time-to-spill (TTS) data that separates overlapping pulses and determines their energy-dependence. The crucially important initial guess solution is determined by wavelet-denoising a time series of delta-function photon arrival times, and then locating, modeling, and removing successive pulses (analogously to the clean deconvolution procedure of radio astronomy). The final model is then determined by minimizing a Bayesian likelihood function Pr(model|data) based on the Poisson probability distribution. This effort will yield statistical information on pulse rise-time, decay-time, peakedness, and amplitudes, plus their energy dependences—both within a single burst and for a large ensemble of bursts.