Observational differences between Swift GRB classes

摘要

There are accumulating evidences that GRBs have an intermediate group, beside the short and long classes. Based on the observational data available in the Swift table we compared the observational gamma and X ray properties of GRBs making use the discriminant analysis of the multivariate mathematical statistics. The analysis resulted in two canonical discriminating functions giving the maximum separation between the groups. The first discriminating function is dominated by the gamma and X-ray fluence while the second one is almost identical with the photon index.