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arXiv · astro-ph/9803237

Evidence for a Galactic gamma ray halo

D. D. Dixon·D. H. Hartmann·E. D. Kolaczyk·J. Samimi·R. Diehl·G. Kanbach·H. Mayer-Hasselwander·A. W. Strong
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Abstract

We present quantitative statistical evidence for a $γ$-ray emission halo surrounding the Galaxy. Maps of the emission are derived. EGRET data were analyzed in a wavelet-based non-parametric hypothesis testing framework, using a model of expected diffuse (Galactic + isotropic) emission as a null hypothesis. The results show a statistically significant large scale halo surrounding the center of the Milky Way as seen from Earth. The halo flux at high latitudes is somewhat smaller than the isotropic gamma-ray flux at the same energy, though of the same order (O(10^(-7)--10^(-6)) ph/cm^2/s/sr above 1 GeV).

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D. D. Dixon, D. H. Hartmann, E. D. Kolaczyk, J. Samimi, R. Diehl, G. Kanbach, H. Mayer-Hasselwander, A. W. Strong. 1998-08-19. Evidence for a Galactic gamma ray halo. https://doi.org/10.1016/s1384-1076(98)00024-4

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