不同卫星伽玛νF_ν暴谱的峰值能量分布

The Peak Energy Distribution of the νF_ν Spectra Obtained by Different Satellites

伽玛暴是宇宙中最剧烈的爆发现象之一,观测伽玛暴预警和暂现源实验卫星(Compton Gamma-Ray Observatory/Bursts and Transient Source Experiment,BATSE)、高能暂现源探测卫星(High Energy Transient Explorer,HETE)和Fermi提供了大量的伽玛暴样本,对这些数据进行分析,用统计的方法寻找其中蕴含的伽玛暴辐射物理信息是必要的。伽玛暴能谱νFν的峰值能量Ep是伽玛暴一个很重要的物理量,并且每个暴的峰值能量不同。研究比较不同仪器观测的伽玛暴νFν谱的峰值能量Ep分布,发现伽玛暴的峰值能量Ep分布很宽,不同仪器的Ep分布相似,BATSE样本Ep分布的峰值比HETE-2和Fermi样本的Ep峰值要大一些,这可能是由于选取的BATSE样本都是亮暴造成的。3种仪器观测的Log N-Log Ep分布也没有显著差异。即从统计学的角度上讲,3种暴的Ep分布没有本质不同,不同仪器观测到的伽玛暴的辐射物理信息应该是一致的。

Gamma-ray bursts（ GRBs） is one of the most violent events in the universe. The gamma-ray telescope CGRO / BATSE（ Compton Gamma-Ray Observatory / Bursts and Transient Source Experiment） consists of 8 Large Na I Area Detectors（ LADs） and it can detect more than 2700 GRBs due to its wide energy coverage（-25 ke V to-1Me V） and large field of view. Fermi（ Fermi Gamma-Ray Space Telescope） can measure the spectra in a very wide energy band（ from 8ke V to more than 300 Ge V）. It opens a new era of observational astronomy in the energetic gamma-ray band. Another mission HETE-2,as the first satellite entirely dedicated to the detection and study of GRBs,the FREGATE（ French Gamma Telescope） gamma ray detector on board of HETE-2 is sensitive to photons in the energy band of ~ 10 to ~ 400 ke V. This sensitivity range,extended towards low energies,allows us to explore the emission of GRBs in hard X-rays and X-ray flashes（ XRFs）,which extend the Epdistribution to a few ke V. These three satellites together provide us plenty of GRB samples. It is necessary to perform a detailed analysis of these data,and to find the contained GRB radiation physics information using statistical methods. The peak energy of the νFνspectra Epis an important quantity of the GRBs and it is dramatically different from burst to burst. We study the peak energy Epdistribution of the νFνspectra of GRBs with samples of 57 bursts observed by HETE-2,156 bright bursts observed by BATSE and 1407 bursts observed by Fermi. Our results show that the distribution of Epis wide,and the distribution profile of the observed Epfrom BATSE,HETE-2 and Fermi / GBM GRBs is consistent. The peak energy of the BATSE sample is statistically higher than that of HETE-2 and Fermi samples,but maybe this is because the selection of the BATSE samples are bright bursts. And the distributions of Log N-Log Epobserved by these three satellites are also consistent with each other. These results indicate that the Epdistributions of GRBs observed by different satellites are similar,and the radiation physics of of these GRBs may be similar.