A possible origin of gamma rays from the Fermi Bubbles

Satyendra Thoudam
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引用次数: 2

Abstract

One of the most exciting discoveries of recent years is a pair of gigantic gamma-ray emission regions, the so-called Fermi bubbles, above and below the Galactic center. The bubbles, discovered by the Fermi space telescope, extend up to 50° in Galactic latitude and are 40° wide in Galactic longitude. The gamma-ray emission is also found to correlate with radio, microwave and X-rays emission. The origin of the bubbles and the associated non-thermal emissions are still not clearly understood. Possible explanations for the non-thermal emission include cosmic-ray injection from the Galactic center by high speed Galactic winds/jets, acceleration by multiple shocks or plasma turbulence present inside the bubbles, and acceleration by strong shock waves associated with the expansion of the bubbles. In this paper, I will discuss the possibility that the gamma-ray emission is produced by the injection of Galactic cosmic-rays mainly protons during their diffusive propagation through the Galaxy. The protons interact with the bubble plasma producing π°-decay gamma rays, while at the same time, radio and microwave synchrotron emissions are produced by the secondary electrons/positrons resulting from the π± decays.

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伽马射线可能来自费米气泡
近年来最令人兴奋的发现之一是在银河系中心的上方和下方发现了一对巨大的伽马射线发射区,即所谓的费米气泡。这些气泡是由费米太空望远镜发现的,在银河系纬度上延伸到~ 50°,在银河系经度上延伸到~ 40°。伽玛射线发射也被发现与无线电、微波和x射线发射有关。气泡的起源和相关的非热辐射仍不清楚。对非热辐射的可能解释包括:银河系中心高速星系风/喷流注入的宇宙射线,气泡内部存在的多重冲击或等离子体湍流加速,以及与气泡膨胀相关的强冲击波加速。在本文中,我将讨论伽马射线发射是由银河系宇宙射线(主要是质子)在银河系扩散传播过程中注入而产生的可能性。质子与气泡等离子体相互作用产生π°衰变伽马射线,同时π±衰变产生的二次电子/正电子产生无线电和微波同步辐射。
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Contents Editorial Board Author index Hybrid Simulations of Particle Acceleration at Shocks Using optical lines to study particle acceleration at supernova remnants
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