Consistent scenarios for cosmic-ray excesses from Sommerfeld-enhanced dark matter annihilation

Douglas P. Finkbeiner, Lisa Goodenough, Tracy R. Slatyer, Mark Vogelsberger, Neal Weiner

    Research output: Contribution to journalArticlepeer-review


    Anomalies in direct and indirect detection have motivated models of dark matter consisting of a multiplet of nearly-degenerate states, coupled by a new GeV-scale interaction. We perform a careful analysis of the thermal freezeout of dark matter annihilation in such a scenario. We compute the range of "boost factors" arising from Sommerfeld enhancement in the local halo for models which produce the correct relic density, and show the effect of including constraints on the saturated enhancement from the cosmic microwave background (CMB). We find that boost factors from Sommerfeld enhancement of up to ∼ 800 are possible in the local halo. When the CMB bounds on the saturated enhancement are applied, the maximal boost factor is reduced to ∼ 400 for 1-2 TeV dark matter and sub-GeV force carriers, but remains large enough to explain the observed Fermi and PAMELA electronic signals. We describe regions in the DM mass-boost factor plane where the cosmic ray data is well fit for a range of final states, and show that Sommerfeld enhancement alone is enough to provide the large annihilation cross sections required to fit the data, although for light mediator masses (mφ200 MeV) there is tension with the CMB constraints in the absence of astrophysical boost factors from substructure. Additionally, we consider the circumstances under which WIMPonium formation is relevant and find for heavy WIMPs (2TeV) and soft-spectrum annihilation channels it can be an important consideration; we find regions with mχ2.8TeV that are consistent with the CMB bounds with (600-700) present-day boost factors.

    Original languageEnglish (US)
    Article number002
    JournalJournal of Cosmology and Astroparticle Physics
    Issue number5
    StatePublished - May 2011


    • dark matter experiments
    • dark matter theory

    ASJC Scopus subject areas

    • Astronomy and Astrophysics


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