I review our current understanding of positron sources in the Galaxy, on the basis of the reported properties of the observed 511 keV annihilation line. It is argued here that most of the disk positrons propagate away from the disk and the resulting low surface brightness annihilation emission is currently undetectable by SPI/INTEGRAL. It is also argued that a large fraction of the disk positrons may be transported via the regular magnetic field of the Galaxy into the bulge and annihilate there. These ideas may alleviate current difficulties in interepreting INTEGRAL results in a "conventional" framework.
Positron propagation in semi-relativistic plasmas: particle spectra and the annihilation line shape
通过直接求解Fokker-Planck方程，用$kT<m_ec^2$研究了湮灭、粒子逃逸和注入对热氢等离子体中稳态正电子分布形式的影响。我们表明，逃逸的正电子的形式的电子-正电子对和/或对等离子体的正电子分布上造成的影响，在某些情况下，强烈偏离麦克斯韦。此外，我们提出了准确的公式，能量交换率，由于库仑散射，韧致辐射，康普顿散射在克莱因-西科政权的损失。提出了用SIGMA望远镜在苍蝇座新星和1 E 1740.7-2942上观测到的湮灭特征是由于正电子/电子在热等离子体中的慢化和湮灭引起的，估算了电子数密度和发射区的大小。我们表明，在苍蝇座新星的情况下，所观察到的辐射是来自一对等离子体流（$n_{e^+}\approx n_{e^-}$），而不是从气体云。我们认为，两种模式可能是相关的1 E 1740.7-2942源：湮灭（氢）等离子体$n_{e^+}\la n_{e^-}$在休息，和湮灭对等离子体流，其中涉及到从源环境的物质。
Anti-proton and positron Cosmic Rays from Dark Matter annihilation around Intermediate Mass Black Holes
中等质量黑洞（IMBH）是超大质量黑洞（SMBH）的候选者，其中一些可能仍然在银河系中徘徊。在湮灭暗物质（DM）的背景下，它们预计会驱动巨大的湮灭率，因此可能会显着增强预期来自星系晕DM湮灭的初级宇宙射线（CR）。在这篇论文中（原始论文是Brun et al. 2007），我们简要解释了估算这种奇异贡献对反质子和正电子CR谱的方法，以及与IMBH性质相关的统计不确定性。我们发现，为了$10^4$的外来通量的助推因子，但与非常大的统计不确定性。
The positron excess observed by the PAMELA experiment may come from dark matter annihilation, if the annihilation cross section is large enough. We show that the dark matter annihilation scenarios to explain the positron excess may also be compatible with the discrepancy of the cosmic lithium abundances between theory and observations. The wino-like neutralino in the supersymmetric standard model is a good example for it. This scenario may be confirmed by Fermi satellite experiment.
