The cosmic-ray positron excess from a local Dark Matter over-density

TL;DR

This paper proposes that the observed cosmic-ray positron excess can be explained by dark matter annihilations within a local over-density, fitting multiple observational data without requiring leptophilic dark matter models.

Contribution

It demonstrates that local dark matter over-density can account for positron excess, fitting data across positrons, antiprotons, and gamma rays with standard dark matter candidates.

Findings

Dark matter annihilation in local over-density explains positron excess

Fits data without leptophilic dark matter assumptions

Standard Wino dark matter candidates are compatible

Abstract

We show that the cosmic-ray positron excess measured by PAMELA and AMS could be induced by Dark Matter annihilations in a local over-density. In such a context leptophilic DM is not needed and good fits to positron data, in agreement with antiproton and gamma-ray measurements, are obtained for DM annihilations to $WW$, $hh$, $ZZ$, $ t \bar t$, $b \bar b$, $q\bar q$ channels. The classic Dark Matter candidates, such as the pure supersymmetric Wino with standard thermal annihilation cross-section, can fit the positron excess, without invoking any additional assumption on Dark Matter properties.