Search for the Gamma-Ray Burst Groups with the Fermi Satellite

A sampl e of 488 gamma-ray bursts (GRBs), measured by the Fermi satellite, is studied statistically with respect to the durations. Standard statistical tests are used, such as the F-test and the maximum likelihood ratio test, in order to ask for the number of components in a Gaussian mixture model of the GRB duration probability density in this database. Using the durations T90 and T50, the F-test and also the maximum likelihood test, did not find any statistically significant intermediate group.