Study On Observational Search And Classification Problems Of Gamma-Ray Bursts

Gamma-ray burst（GRB）is a sudden enhancement of gamma rays in the sky and is one of the most energetic celestial outburst events in the universe.Since the discovery of GRBs was made public in 1973 until now,the research on GRBs has been close to half a century,during which the research on the origin and radiation mechanism of GRBs has made great progress,but now the classification of GRB is still a controversial topic.According to the classical classification criteria,GRBs are divided into long bursts and short bursts in terms of observation and physical origin.In observation,the T₉₀ is equal to two seconds as the limit,longer than two seconds is a long burst,less than two seconds is a short burst.In terms of physical origin,long GRBs are generally thought to originate from massive star core collapse events and short GRBs originate from binary compact star merger.However,with the progress of observation instruments and the accumulation of observation data,more and more GRBs samples that do not meet the classification standard have been found,and the classical classification standard of GRBs is facing questions and challenges.This paper mainly discusses the classification of GRB from the perspectives of data processing,mathematical statistics and physical analysis.We set up a GRB signal search program,and then conducted a search based on the Fermi/GBM burst catalog,and got a number of GRBs samples.Then,according to the limitation of the T90,we propose new time scales:T_on and T₁₀₀ to describe the duration of GRB,and further discuss the classification of GRB by analyzing the duration of bright burst samples.The structure of this paper is as follows.The first chapter mainly introduces the history of GRB observation and discusses the problems faced by GRB classification and the limitations of T₉₀.The second chapter introduces the algorithms of baseline evaluation for the background emission in the detectors,and discusses the significance algorithm for GRB signal detection with many details.The third chapter mainly introduces the search process of GRB samples,the calculation process of T_on and T₁₀₀,and the authentication and processing of special samples.we perform a statistical analysis of the duration of bright burst samples and focus on the effect of quiet periods in gamma bursts on their classification.The fifth chapter is the summary of the full text and the prospect of the future.