标题： EGRET望远镜对各向同性弥散伽马射线背景的观测 显示英文标题

标题： Observations of the Isotropic Diffuse Gamma-ray Background with the EGRET Telescope

摘要： 在30-10,000 MeV能谱范围内的各向同性弥散伽马射线背景（IDGRB）最早在20世纪70年代初通过SAS-2仪器的测量结果报告。为了提取迄今为止对IDGRB的最佳测量结果，分析了过去4年中搭载在康普顿伽马射线天文台（CGRO）上的高能伽马射线实验望远镜（EGRET）记录的数据。介绍了对EGRET仪器背景的详细分析，以证明可以从EGRET数据中提取出未受污染的数据集。提出了一个高纬度银河系弥散前景发射的模型，并确认了IDGRB的存在。介绍了对该背景的空间和光谱分析。此外，对高银河纬度的点源进行了分析，以揭示河外源群体的存在。研究了该群体的特性，并报告了其通量分布的模型。通过波动分析探讨了IDGRB是否由未分辨的点源组成。最后，通过模拟未来的伽马射线望远镜——伽马射线大型面积空间望远镜（GLAST）来探讨伽马射线天文学的可能未来方向。描述了GLAST的基本设计，并评估了其科学性能。展示了该望远镜检测1,000-10,000个新河外源的能力，并考虑了其对IDGRB研究的可能影响。 显示英文摘要

摘要： An Isotropic Diffuse Gamma-Ray Background (IDGRB) in the spectral range 30-10,000 MeV was first reported in the early 1970's using measurements made by the SAS-2 instrument. Data recorded by the Energetic Gamma Ray Experiment Telescope (EGRET) on board the Compton Gamma Ray Observatory (CGRO) over the last 4 years are analysed in order to extract the best measurement yet made of the IDGRB. Extensive analysis of the EGRET instrumental background is presented in order to demonstrate that an uncontaminated data set can be extracted from the EGRET data. A model of the high latitude galactic diffuse foreground emission is presented and the existence of an IDGRB is confirmed. Spatial and spectral analysis of this background is presented. In addition, point source analysis at high galactic latitudes is performed to reveal the existence of a population of extragalactic sources. The characteristics of this population are examined and models of its flux distribution are reported. The question of whether the IDGRB is composed of unresolved point sources is addressed using fluctuation analysis. Finally, possible future directions for gamma ray astronomy are examined through simulations of a future gamma ray telescope: the Gamma-ray Large Area Space Telescope (GLAST). The GLAST baseline design is described and its scientific performance is evaluated. The ability of this telescope to detect 1,000-10,000 new extragalactic sources is demonstrated and the likely impact on the study of the IDGRB is considered.