HESS constraints on dark matter annihilations towards the sculptor and carina dwarf galaxies

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2011

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The Sculptor and Carina dwarf spheroidal galaxies were observed with the H.E.S.S. Cherenkov telescope array between January 2008 and December 2009. The data sets consist of a total of 11.8 h and 14.8 h of high quality data, respectively. No gamma-ray signal was detected at the nominal positions of these galaxies above 220 GeV and 320 GeV, respectively. Upper limits on the gamma-ray fluxes at 95% CL assuming two forms for the spectral energy distribution (a power law shape and one derived from dark matter annihilation) are obtained at the level of 10-13-10-12 cm-2 s-1 in the TeV range. Constraints on the velocity weighted dark matter particle annihilation cross section for both Sculptor and Carina dwarf galaxies range from 〈σv〉 ∼ 10-21 cm3 s-1 down to 〈σv〉 ∼ 10-22 cm3 s -1 depending on the dark matter halo model used. Possible enhancements of the gamma-ray flux are studied: the Sommerfeld effect, which is found to exclude some dark matter particle masses, the internal Bremsstrahlung and clumps in the dark-matter halo distributions. © 2011 Published by Elsevier B.V.

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Forschungsinformationssystem der UHH

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Quelldatensatz: oai:www.edit.fis.uni-hamburg.de:publications/099dc153-4dbd-4db3-8314-d641d0d3c6c8