The diffuse Galactic γ-rays from dark matter annihilation

Xiao-Jun Bi,Juan Zhang,Qiang Yuan,Jian-Li Zhang,Hongsheng Zhao

doi:10.1016/j.physletb.2008.08.041

Xiao-Jun Bi, Juan Zhang + Show 3 more

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https://doi.org/10.1016/j.physletb.2008.08.041

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Abstract

The diffuse Galactic γ-rays from EGRET observation shows excesses above 1 GeV in comparison with the expectations from conventional Galactic cosmic ray (CR) propagation model. In the work we try to solve the “GeV excess” problem by dark matter (DM) annihilation in the frame of supersymmetry (SUSY). Compared with previous works, there are three aspects improved in this work: first, the direction-independent “boost factor” for diffuse γ-rays from dark matter annihilation (DMA) is naturally reproduced by taking the DM substructures into account; second, there is no need for renormalization of the diffuse γ-ray background produced by CRs; last but not the least, in this work our new propagation model can give consistent results of both diffuse γ-rays and antiprotons, by directly adding the signals from DMA to the diffuse γ-ray background. This is a self-consistent model among several possible scenarios at present, and can be tested or optimized by the forthcoming experiments such as GLAST, PAMELA and AMS02.

Highlights

The diffuse Galactic γ-rays are produced via interaction of cosmic ray (CR) with the interstellar medium and radiation field
The spectrum of the diffuse γ rays measured by EGRET shows an excess above 1 GeV [1] in comparison with the prediction based on the conventional CR model, whose nucleus and electron spectra are consistent with the locally observed data
A harder nucleon spectrum with power-law index of −2.4 ∼ 2.5 has been proposed in Ref. [2] to solve the “GeV excess” problem

Summary

Introduction

The diffuse Galactic γ-rays are produced via interaction of CRs with the interstellar medium and radiation field. The spectrum of the diffuse γ rays measured by EGRET shows an excess above 1 GeV [1] in comparison with the prediction based on the conventional CR model, whose nucleus and electron spectra are consistent with the locally observed data.

Results

Conclusion