Time series characteristics of gamma ray bursts observed by Fermi

The light curves corresponding to the prompt emission of Gamma-ray bursts (GRBs) show complex structures with no well-defined morphology as well as exhibi-ting variabilities from milisecond to tens of seconds. Variability studies of GRB light curves are expected to provide important clues on the nature of the underlying physical mechanisms. A number of models have been put forward to describe the time structure of GRB light curves. These include the internal shock and photosphe-ric models which suggest that it is the activity of the central engine that is responsible from the variability of the light curves. Data and models models suggest the existan-ce of at least two time scales suggesting more than one mechanism that leads to the prompt emission. It is important to extract the temporal variability of these sources in different energy bands in order to better understand the prompt emissions of GRBs and to test the various components in the different models. In this thesis, the tempo-ral properties of GRBs, observed with the Fermi/LAT satellite, are analyzed with the wavelet method in the energy range of 30 MeV-300 GeV. Results are compared with the temporal properties of GRBs observed with the Fermi / GBM satellite at lower energies (8 keV-1 MeV) to investigate the similarities and the differences. Key Words: Gamma ray bursts; Minimum time scale:Mts; Fermi/Lat