Abstract
The CACTUS atmospheric Cherenkov telescope collaboration recently reporteda gamma-ray excess from the Draco dwarf spheroidal galaxy. Draco features avery low gas content and a large mass-to-light ratio, suggesting as a possibleexplanation annihilation of weakly interacting massive particles (WIMPs) in theDraco dark-matter halo. We show that with improved angular resolution, futuremeasurements can determine whether the halo is cored or cuspy, as well as its scale radius.We find the relevant WIMP masses and annihilation cross sections and showthat supersymmetric models can account for the required gamma-ray flux. Theannihilation cross section range is found to be not compatible with a standard thermalrelic dark-matter production. We compute for these supersymmetric models theresulting Draco gamma-ray flux in the GLAST energy range and the rates for directneutralino detection and for the flux of neutrinos from neutralino annihilationin the Sun. We also discuss the possibility that the bulk of the signal detectedby CACTUS comes from direct WIMP annihilation to two photons and pointout that a decaying-dark-matter scenario for Draco is not compatible with thegamma-ray flux from the Galactic centre and in the diffuse gamma-ray background.
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