Uncertainties of the antiproton flux from Dark Matter annihilation in comparison to the EGRET excess of diffuse gamma rays

TL;DR

This paper examines the uncertainties in predicting antiproton fluxes from dark matter annihilation, showing that anisotropic propagation models can reconcile these predictions with observations and the gamma-ray excess observed by EGRET.

Contribution

It introduces more realistic anisotropic propagation models that align dark matter annihilation signals with observed antiproton fluxes and gamma-ray excesses.

Findings

Anisotropic models allow antiproton fluxes consistent with observations.

Dark matter annihilation can explain the EGRET gamma-ray excess.

Conventional isotropic models overpredict antiproton fluxes.

Abstract

The EGRET excess of diffuse Galactic gamma rays shows all the features expected from dark matter annihilation (DMA): a spectral shape given by the fragmentation of mono-energetic quarks, which is the same in all sky directions and an intensity distribution of the excess expected from a standard dark matter halo, predicted by the rotation curve. From the EGRET excess one can predict the flux of antiprotons from DMA. However, how many antiprotons arrive at the detector strongly depends on the propagation model. The conventional isotropic propagation models trap the antiprotons in the Galaxy leading to a local antiproton flux far above the observed flux. According to Bergstrom et. al. this excludes the DMA interpretation of the EGRET excess. Here it is shown that more realistic anisotropic propagation models, in which most antiprotons escape by fast transport in the z-direction, are consistent with the B/C ratio, the antiproton flux and the EGRET excess from DMA.