Ph.D. Defense

Gamma-ray bursts (GRBs) are the most luminous explosions in the universe. They are generally classified into two types according to the durations of their Γ-ray emission. Progenitors of short-duration GRBs (SGRBs) are believed to be compact stars binaries (e.g., neutron stars and black holes; also known as Type I GRBs by their physical origin). For long-duration GRBs (LGRBs) they are thought to be originated from core-collapse of massive stars (Type II). However, the duration criterion is not always reliable. In this dissertation, I propose a multi-parameter method based on multi-wavelength data of GRBs to classify them by their physical nature, i.e., Type I or Type II. With a similar method, we search for SGRB-less X-ray transients with neutron star binaries as progenitors. The multi-wavelength studies of GRBs also allow for a study of the evolution of GRB population through the cosmic time.