伽玛射线暴高能辐射的新特征研究

Recently, the high-energy gamma-ray emission (HE) from Gamma-Ray Bursts (GRB) exhibits the onset delay and temporal extended emission, and its spectrum has a hard power-law component and/or an exponential cutoff at the end of HE band. These features lead to a hot topic of GRB research, but it also raises the issue that how to explain them. Can the external origin account for the long-lasting HE, or both the external and internal origins contributes to the HE? In which case, the synchrotron and the synchrotron self-Compton dominate the HE? How to power the very high-energy emission (VHE, >300GeV) from GRB 190114C that detected by MAGIC? Those issues are all needed to be solved. In this project, we will decompose the components in the light-curves and spectra of 11-yrs Fermi-LAT GRBs since the Fermi launched, probe into the new features of the HE in GRBs by employing the large sample statistical method and carry out the research on these scientific issues. This project will help study for the shock properties, the distribution of GRB-surrounding medium, and will make some suggestion on the proposal of the VHE detection from GRBs observed by Chinese LHAASO.

近年来，伽玛射线暴的高能伽玛辐射（大于100MeV）被发现在时间上呈现了延迟启动和延展辐射、在能谱上出现了硬成分和高能末端的指数截断，这些新特征的出现掀起了高能辐射的研究热潮，同时也引发了解释这些新特征的争议。伽玛暴长期的高能伽玛辐射是共同的外激波起源，还是内、外激波过程的叠加？同步辐射和同步自康普顿辐射分别在什么情况下主导？MAGIC观测到GRB 190114C的甚高能辐射（大于300GeV）如何解释？这些都是亟待解决的科学问题。本项目拟利用11年的Fermi-LAT暴样本，提取和统计它们的高能伽玛辐射光变形态和能谱成分，利用大样本统计方法来探究伽玛暴高能辐射的新特征，并就以上科学争议开展研究。本项目有助于探究伽玛暴的激波特点、环境介质分布等重要物理性质，也能对我国LHAASO的伽玛暴甚高能辐射探测方案提出一些建议。

本项目完成了2008年8月年至2022年12月被费米卫星探测到有高能探测的伽玛暴，建立了伽玛暴高能辐射数据库，基于该数据库我们找出了多个伽马暴的额外能谱成分，分析了这些成分的统计特征，例如峰值能量、额外成分光子谱指数、各成分流量等，对这些观测量进行了相关性分析。我们用轻子辐射模型和强子辐射模型分别给出了高能辐射的限定，并研究了这些暴的低能辐射可能对这些辐射模型的支持和排除依据。本项目研究了对多个极亮暴或极短暴，发现了黑体成分可能存在的证据，并得到了这些成分与伽马暴瞬时高能伽马辐射存在着内在联系的初步证据。项目执行期间发表了SCI研究论文9篇，其中本领域顶级期刊5篇，培养了2人次省级人才工程，培养了6名研究生，获得了“江西省天文学研究成果一等奖”的奖励。