Excited Dark Matter versus PAMELA/Fermi

TL;DR

This paper examines whether multicomponent dark matter models can simultaneously explain the 511 keV gamma-ray excess and high-energy electron/positron excesses observed by PAMELA and Fermi, considering astrophysical constraints.

Contribution

It evaluates the viability of a single dark matter model to explain multiple cosmic ray anomalies and identifies mass and profile constraints.

Findings

Models fit 511 keV and PAMELA excesses for dark matter mass < 400 GeV.

Fermi lepton excess cannot be explained simultaneously.

Cuspy halo profiles conflict with inverse Compton constraints at higher masses.

Abstract

Excitation of multicomponent dark matter in the galactic center has been proposed as the source of low-energy positrons that produce the excess 511 keV gamma rays that have been observed by INTEGRAL. Such models have also been promoted to explain excess high-energy electrons/positrons observed by the PAMELA, Fermi/LAT and H.E.S.S. experiments. We investigate whether one model can simultaneously fit all three anomalies, in addition to further constraints from inverse Compton scattering by the high-energy leptons. We find models that fit both the 511 keV and PAMELA excesses at dark matter masses M < 400 GeV, but not the Fermi lepton excess. The conflict arises because a more cuspy DM halo profile is needed to match the observed 511 keV signal than is compatible with inverse Compton constraints at larger DM masses.