We review the current understanding of the diffuse gamma-ray background (DGRB). The DGRB is what remains of the total measured gamma-ray emission after the subtraction of the resolved sources and of the diffuse Galactic foregrounds. It is interpreted as the cumulative emission of sources that are not bright enough to be detected individually. Yet, its exact composition remains unveiled. Well-established astrophysical source populations (e.g. blazars, misaligned AGNs, star-forming galaxies and millisecond pulsars) all represent guaranteed contributors to the DGRB. More exotic scenarios, such as dark matter annihilation or decay, may contribute as well. In this review, we describe how these components have been modeled in the literature and how the DGRB can be used to provide valuable information on each of them. We summarize the observational information currently available on the DGRB, paying particular attention to the most recent measurement of its intensity energy spectrum by the Fermi LAT Collaboration. We also discuss the novel analyses of the auto-correlation angular power spectrum of the DGRB and of its cross-correlation with tracers of the large-scale structure of the Universe. New data sets already (or soon) available are expected to provide further insight on the nature of this emission. By summarizing where we stand on the current knowledge of the DGRB, this review is intended both as a useful reference for those interested in the topic and as a means to trigger new ideas for further research.
The Dark Matter Contribution to Galactic Diffuse Gamma Ray Emission
费米大面积望远镜（LAT）对弥漫的银河伽马射线发射（DGE）的观测，使我们能够对宇宙射线和星际介质进行详细的研究。然而，银河系内部的扩散发射模型低估了费米-LAT数据在能量超过几个GeV，并暗示可能的非天体物理来源，包括暗物质（DM）的湮灭或衰变。我们提出了一个研究可能的排放组件DM使用高分辨率的通过Lactea II N体模拟银河系大小的DM晕。我们生成DM湮灭和衰变信号的全天空地图，其中包括主机密度分布的绝热收缩的建模，索末菲增强DM湮灭，$p$波湮灭，和衰减DM。我们将我们的结果与费米-LAT团队在不同天空区域（包括银河系中心，银河系高纬度和银河系反中心）制作的DGE模型进行比较。这项工作提供了可能的模板，以适应观测数据，其中包括贡献的subhalo人口DM伽马射线发射，与意义取决于湮灭/衰变通道和银河系地区正在考虑。
Spectral and spatial variations of the diffuse gamma-ray background in the vicinity of the Galactic plane and possible nature of the feature at 130 GeV
Current and Future Constraints on Dark Matter from Prompt and Inverse-Compton Photon Emission in the Isotropic Diffuse Gamma-ray Background
我们进行了详细的检查，从提示和逆康普顿发射光子，包括模型相关和模型无关的边界的湮灭和衰变暗物质模型的电流约束。我们还表明，所观察到的各向同性弥散伽马射线背景（DGRB），这提供了一个最保守的约束模型的湮灭弱尺度暗物质粒子，可能会提高其灵敏度的一个因素~2至3（95% C. L.）。因为费米-LAT实验通过五年的观测解决了DGRB贡献的blazar源。对于我们的预测，我们采用的结果约束的光度依赖的密度演化加上blazar光谱能量分布序列模型，这是由DGRB和blazar源计数分布函数的约束。
