用羊八井ASγ实验数据寻找TeV能区的γ射线暴

Search for TeV GRBs using Tibet ASγ data

γ射线暴的TeV能区辐射对研究其起源、辐射机制等是非常重要的.利用西藏羊八井ASγ实验三期阵列的重建数据,通过在给定的小天区和时间间隔内寻找较高显著性事例团的方法对TeV能区的γ射线暴进行了寻找,在计算过程中采用"等天顶角法"来估计背景.工作中采用了两种途径来寻找γ射线暴,一种是与卫星γ射线暴的符合寻找,另一种是全天区独立寻找.结果发现少量事例团对背景有明显超出,考虑试验次数后,其超出还不足以认定为γ射线暴.通过MonteCarlo模拟,给出了在95%置信水平下,到达大气顶部流强上限的估计值为3.32×10-9—1.24×10-7cm-2s-1.

TeV energy emission from gamma ray bursts （GRB） is very important for studying the origin and the radiation mechanism of GRB. Searching for TeV GRBs is carried out by using the Tibet ASγ＇ data. A GRB candidate is a shower cluster appearing in a given small sky window and a given time interval. An equi-zenith-angle method is used to estimate the background. In this analysis, two methods are applied in searching for possible GRB＇s signals, one considers the coincidence with satellite GRB data and the other doesn＇t. No significant TeV GRBs is detected in either case. The upper flux limit on top of the atmosphere at the 95% confidence level is estimated to be about 3.32× 10-9--1.24×10-7 cm-2·s-1 accordingly.