On possible interpretations of the high energy electron-positron spectrum measured by the Fermi Large Area Telescope

Abstract

The Fermi-LAT experiment recently reported high precision measurements of the spectrum of cosmic-ray electrons-plus-positrons (CRE) between 20 GeV and 1 TeV. The spectrum shows no prominent spectral features, and is significantly harder than that inferred from several previous experiments. Here we discuss several interpretations of the Fermi results based either on a single large scale Galactic CRE component or by invoking additional electron-positron primary sources, e.g. nearby pulsars or particle Dark Matter annihilation. We show that while the reported Fermi-LAT data alone can be interpreted in terms of a single component scenario, when combined with other complementary experimental results, specifically the CRE spectrum measured by H.E.S.S. and especially the positron fraction reported by PAMELA between 1 and 100 GeV, that class of models fails to provide a consistent interpretation. Rather, we find that several combinations of parameters, involving both the pulsar and dark matter scenarios, allow a consistent description of those results. We also briefly discuss the possibility of discriminating between the pulsar and dark matter interpretations by looking for a possible anisotropy in the CRE flux.

29 pages, 12 figures. Final version accepted for publication in Astroparticle Physics

References in corpus (9)

• Secluded WIMP Dark Matter
• Measurement of the Cosmic Ray e+ plus e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope
• Dark Matter and Collider Phenomenology of Universal Extra Dimensions
• Exciting Dark Matter and the INTEGRAL/SPI 511 keV signal
• Dark matter interpretation of recent electron and positron data
• TeV gamma-rays and the largest masses and annihilation cross sections of neutralino dark matter
• High-energy electron observations by PPB-BETS flight in Antarctica
• Cosmic ray lepton puzzle in the light of cosmological N-body simulations
• Cosmic Ray Proton Background Could Explain ATIC Electron Excess

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• Inverse Compton constraints on the Dark Matter e+e- excesses
• Constraints on Dark Matter annihilations from reionization and heating of the intergalactic gas
• Dark Matter Through the Neutrino Portal
• Decaying dark matter with heavy axino
• On discrepancy between ATIC and Fermi data
• Inverse Problem of Cosmic-Ray Electron/Positron from Dark Matter
• Dark Matter Decay and Cosmic Rays