Implications of an astrophysical interpretation of PAMELA and Fermi-LAT data for future searches of a positron signal from dark matter annihilations

TL;DR

This paper examines how astrophysical sources of high-energy positrons, suggested by PAMELA and Fermi-LAT data, increase background noise and affect the detectability of dark matter annihilation signals in future experiments like AMS-02.

Contribution

It analyzes the impact of astrophysical positron backgrounds on dark matter detection prospects and updates the detectable parameter space considering these backgrounds.

Findings

Background increases the required annihilation rate by up to a factor of three.

Detection of dark matter positrons is more challenging due to astrophysical backgrounds.

New detection regions in the (mass, v) plane are identified.

Abstract

The recent data from PAMELA and Fermi-LAT can be interpreted as evidence of new astrophysical sources of high energy positrons. In that case, such astrophysical positrons constitute an additional background against the positrons from dark matter annihilation. In this paper, we study the effect of that background on the prospects for the detection of a positron dark matter signal in future experiments. In particular, we determine the new regions in the (mass, $\sigmav$) plane that are detectable by the AMS-02 experiment for several dark matter scenarios and different propagation models. We find that, due to the increased background, these regions feature annihilation rates that are up to a factor or three larger than those obtained for the conventional background. That is, an astrophysical interpretation of the present data by PAMELA and Fermi-LAT implies that the detection of positrons from dark matter annihilation is slightly more challenging than previously believed.