On possible interpretations of the high energy electron–positron spectrum measured by the Fermi Large Area Telescope
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. In this paper, 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. Finally, 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.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE
- Contributing Organization:
- Fermi LAT Collaboration
- Grant/Contract Number:
- AC02-76SF00515
- OSTI ID:
- 1357437
- Journal Information:
- Astroparticle Physics, Vol. 32, Issue 2; ISSN 0927-6505
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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