Cosmic-ray electron signatures of dark matter

Abstract

There is evidence for an excess in cosmic-ray electrons at about 500 GeV energy, that may be related to dark-matter annihilation. I have calculated the expected electron contributions from a pulsar and from Kaluza-Klein dark matter, based on a realistic treatment of the electron propagation in the Galaxy. Both pulsars and dark-matter clumps are quasi-pointlike and few, and therefore their electron contributions at Earth generally have spectra that deviate from the average spectrum one would calculate for a smooth source distribution. I find that pulsars younger than about 10^5 years naturally cause a narrow peak at a few hundred GeV in the locally observed electron spectrum, similar to that observed. On the other hand, for a density n_c = 10 /kpc^3 of dark-matter clumps the sharp cut-off in the contribution from Kaluza-Klein particles is sometimes more pronounced, but often smoothed out and indistinguishable from a pulsar source, and therefore the spectral shape of the electron excess is insufficient to discriminate a dark-matter origin from more conventional astrophysical explanations. The amplitude of variations in the spectral feature caused by dark matter predominantly depends on the density of dark-matter clumps, which is not well known.

5 pages, 2 figures. Phys. Rev. D, submitted

References in corpus (8)

• Clumps and streams in the local dark matter distribution
• The energy spectrum of cosmic-ray electrons at TeV energies
• New Positron Spectral Features from Supersymmetric Dark Matter - a Way to Explain the PAMELA Data?
• A blueprint for detecting supersymmetric dark matter in the Galactic halo
• The Dark Matter Annihilation Signal from Galactic Substructure: Predictions for GLAST
• TeV gamma-rays and the largest masses and annihilation cross sections of neutralino dark matter
• The survival and disruption of CDM micro-haloes: implications for direct and indirect detection experiments
• Early Annihilation and Diffuse Backgrounds in 1/v WIMP models

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