A Global Test of a Quasi‐universal Gamma‐Ray Burst Jet Model through Monte Carlo Simulations

The possibility that long gamma-ray burst (GRB) jets are structured receivesgrowing attention recently, and we have suggested that most GRBs and theirsofter, less energetic fraternity, X-ray flashes (XRFs), can be understoodwithin a quasi-universal structured jet picture, given that the jet structurefor each individual burst is a Gaussian or similar function. Here we perform aglobal test on such a quasi-universal Gaussian-like structured jet by comparingMonte-Carlo simulation results with a broad spectrum of observational data.Using the same set of input parameters as in the previous work (Zhang et al.2004), we confront the model with more observational constraints. Theseconstraints include the burst redshift distribution, jet break angledistribution, two-dimensional redshift vs. jet break angle distribution,luminosity function, and Log N - Log P distribution. The results indicate thatthe model is generally compatible with the data. This conclusion, together withour previous tests with the observed jet break angle vs. isotropic energy andobserved peak energy vs. fluence relations, suggests that current long GRB andXRF data are generally consistent with such a quasi-standard-energy andquasi-standard-angle jet picture. With future homogeneous burst samples (suchas the one to be retrieved from the Swift mission), the refined GRB jetstructure can be further constrained through a global comparison betweenvarious observed and predicted burst property distributions and relations.Comment: 15 pages, including 7 figures, accepted by Ap