Study On The Multi-band Nature Of Extended Radiation Gamma-ray Bursts

The classification of Gamma-ray Bursts(GRBs) is one of the research focuses in the research area about GRBs. Kouvelitou proposed a duration based classification method by using the first catalog of CGRO/BATSE. With this method, GRBs can be classified to Long GRBs and Short GRBs according to their durations longer than 2s or not. This method is widely accepted and applied. As the size of GRBs datasets increase, there are some tough challenges to this method, especially the uncertainty of GRBs with extended emission in the long-soft classification. This thesis does a systematically discussion about the classification of GRBs by using two widely used method, Gaussian Mixture Model and Maximum Likelihood Estimation. There are also a comparison between datasets from different space satellites(e.g. BATSE, Swift,Fermi and Suzaku). This thesis is organized as follows:(1) A brief introduction about the research of GRBs, includeing satellites, observed features, and the progress of some theoretical research;(2) A short introduction of GRBs with extended emission, We collected the duration and spectral hardness information of such GRBs, and compare their performance with the complete datasets;(3) Display our research about classifying GRBs in datasets of BATSE, Swift,Fermi and Suzaku satellites by using Gaussian Mixture Model and Expectation Maximization Algorigthm;(4) Display our research about the two dimensional(T90?HR) classification of the redshift-known Swift GRBs;(5) A summarize of my work while studying for the Master Degree, follows the thought and expectation about future work.