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Fermi/LAT observations of dwarf galaxies highly constrain a dark matter interpretation of excess positrons seen in AMS-02, HEAT, and PAMELA
KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
2016 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, Vol. 2016, no 3, 033Article in journal (Refereed) PublishedText
Abstract [en]

It is shown that a Weakly Interacting Massive dark matter Particle (WIMP) interpretation for the positron excess observed in a variety of experiments, HEAT, PAMELA, and AMS-02, is highly constrained by the Fermi/LAT observations of dwarf galaxies. In particular, this paper examines the annihilation channels that best fit the current AMS-02 data (Boudaud et al., 2014), specifically focusing on channels and parameter space not previously explored by the Fermi/LAT collaboration. The Fermi satellite has surveyed the γ-ray sky, and its observations of dwarf satellites are used to place strong bounds on the annihilation of WIMPs into a variety of channels. For the single channel case, we find that dark matter annihilation into {b,e+e-, μ+μ-, τ+τ-,4-e or 4-τ } is ruled out as an explanation of the AMS positron excess (here b quarks are a proxy for all quarks, gauge and Higgs bosons). In addition, we find that the Fermi/LAT 2σ upper limits, assuming the best-fit AMS-02 branching ratios, exclude multichannel combinations into b and leptons. The tension between the results might relax if the branching ratios are allowed to deviate from their best-fit values, though a substantial change would be required. Of all the channels we considered, the only viable channel that survives the Fermi/LAT constraint and produces a good fit to the AMS-02 data is annihilation (via a mediator) to 4-μ, or mainly to 4-μ in the case of multichannel combinations.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2016. Vol. 2016, no 3, 033
Keyword [en]
cosmic ray experiments, dark matter experiments, gamma ray experiments
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-187220DOI: 10.1088/1475-7516/2016/03/033ScopusID: 2-s2.0-84961737527OAI: oai:DiVA.org:kth-187220DiVA: diva2:932350
Note

QC 20160601

Available from: 2016-06-01 Created: 2016-05-18 Last updated: 2016-06-03Bibliographically approved

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Savage, Christopher
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