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

By D. Grasso, S. Profumo, A. Strong, L. Baldini, R. Bellazzini, E. Bloom, J. Bregeon, G. D. Bernardo, D. Gaggero, N. Giglietto and 13 more. 2009

262 citations recorded by the source corpus.

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.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/6394845d03b9b8e69692596a8ce232f28b7e1535

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In Nuclear and High Energy Physics

Citations in the corpus

Astrophysical models for the origin of the positron (2011, background): “[120, 121]), or a few prominent nearby sources, like Geminga or Monogem in [74, 77, 122, 117].”
Dark Matter Candidates from Particle Physics and Methods of Detection (2010, methodology): “The Fermi data may be explained by modifying the spectral index of the cosmic ray background (94).”
SEARCH FOR DARK MATTER SATELLITES USING FERMI-LAT (2012, unknown): “We specifically studied the spurious sources and unassociated sources with spectral indices in the range from 1.0 to 0.7 since a cluster of sources in this range are predicted by some leptophilic dark matter models (Arvanitaki et al. 2009: Grasso et al. 2009).”
Pulsars versus dark matter interpretation of ATIC/PAMELA (2009, background): “served excess is possible if there are no young energetic pulsars in the vicinity of the Earth with Ebr ≪ Einj [27] or there are considerable spatial variations in the energy losses of these particles as they diffuse through the ISM.”
Constraints on dark matter annihilation in clusters of galaxies with the Fermi large area telescope (2010, methodology): “In the right panel, the cluster gammaray constraints are compared to values of the mass and annihilation cross section for dark matter models annihilating to a μμ final state which provide good fits to the Pamela (blue) or Fermi-LAT (orange) ee data [7].”