Abstract This review summarizes INTEGRAL results on two topics: the electron-positron annihilation line and X-ray & Gamma-ray diffuse emission of the Milky Way. The electron-positron annihilation line at 511 keV is the most prominent spectral feature in the gamma-ray spectrum of the Milky Way. From the observational perspective, INTEGRAL has already provided constraints on the total flux, morphology of the annihilation line distribution, the spectral shape of the line and the strength of the three-photon annihilation continuum. In particular, the most salient morphological feature in the all-sky map of the annihilation emission based on INTEGRAL data is the so-called ”Bulge” component, with the characteristic size of ∼ 6 − 10 ∘ and the positrons’ annihilation rate of ∼ 10 43 s − 1 . A more extended ”Disc” component is also present, although its total luminosity is model dependent. The brightness of the Bulge component compared to the Disc is in contrast with other multi-wavelength images of the Milky Way. The annihilation spectrum consists of a line centered at 511 keV and the ortho-positronium continuum. The strength of the latter indicates that the majority of annihilations go via the positronium formation channel. The shape of the annihilation spectrum is consistent with the assumption that most of the positrons annihilate in a warm and partly ionized medium, although more complicated scenarios are also possible. From the theoretical point of view, a successful model should answer three main questions: (i) physical mechanism(s) responsible for production of positrons, (ii) positrons spatial migration (if any) from the production sites, and (iii) physics of annihilation. Remarkably, despite significant progress provided by INTEGRAL in the characterization of the Milky Way annihilation emission, the origin of positrons remains an open question. The essence of the problem is the abundance of positron production channels and the uncertainty in the distance positrons can travel before annihilation. The spectral-imaging mapping of the Milky Way by INTEGRAL provides important constraints on the nature of the Galactic diffuse continuum hard X-rays and soft gamma-rays in the 20 keV – 2 MeV band. Below ~ 60 keV, numerous unresolved objects (accreting white dwarfs) dominate the flux, but their contribution fades away at higher energies. Models of cosmic-ray induced emission suggest that the dominant diffuse component above ~ 60 keV (excluding annihilation emission) is inverse Compton scattering from GeV electrons on interstellar radiation fields. Non-thermal bremsstrahlung contributes at a lower level. These models are consistent with the continuum spectrum observed by INTEGRAL and COMPTEL.

中文翻译：

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银河系正负电子湮灭辐射和X射线和伽马射线漫射的INTEGRAL结果

摘要 本文综述了INTEGRAL 在两个主题上的结果：电子-正电子湮灭线和银河系的X 射线和伽马射线漫发射。511 keV 的正负电子湮没线是银河系伽马射线光谱中最突出的光谱特征。从观测的角度来看，INTEGRAL已经对总通量、湮灭线分布的形态、线的光谱形状和三光子湮没连续谱的强度进行了约束。特别是，基于 INTEGRAL 数据的湮灭发射全天图中最显着的形态特征是所谓的“Bulge”分量，其特征尺寸为∼ 6 − 10 ∘ ，正电子的湮灭率为∼ 10 43 秒 - 1 。还存在更扩展的“光盘”组件，尽管它的总光度取决于模型。与圆盘相比，凸出部分的亮度与银河系的其他多波长图像形成对比。湮灭光谱由以 511 keV 为中心的线和正正电子连续谱组成。后者的强度表明大部分湮灭是通过正电子形成通道进行的。湮灭谱的形状与大多数正电子在温暖和部分电离的介质中湮灭的假设一致，尽管更复杂的情况也是可能的。从理论的角度来看，一个成功的模型应该回答三个主要问题：（i）负责产生正电子的物理机制，（ii）来自生产地点的正电子空间迁移（如果有的话），以及（iii）物理的湮灭。值得注意的是，尽管 INTEGRAL 在表征银河系湮灭发射方面取得了重大进展，但正电子的起源仍然是一个悬而未决的问题。问题的本质是正电子产生通道的丰富性和正电子在湮灭前可以行进的距离的不确定性。INTEGRAL 对银河系的光谱成像映射为 20 keV – 2 MeV 波段的银河漫射连续谱硬 X 射线和软伽马射线的性质提供了重要的限制。低于 ~ 60 keV，许多未解析的物体（吸积白矮星）在通量中占主导地位，但它们的贡献在更高的能量下逐渐消失。宇宙射线诱导发射模型表明，高于~60 keV（不包括湮灭发射）的主要漫射分量是星际辐射场上 GeV 电子的逆康普顿散射。非热韧致辐射贡献较低。这些模型与 INTEGRAL 和 COMPTEL 观察到的连续谱一致。