Constraints on the Galactic Halo Dark Matter from Fermi-LAT Diffuse Measurements

[摘要] We have performed an analysis of the diffuse gamma-ray emission with the Fermi Large Area Telescope (LAT) inthe Milky Way halo region, searching for a signal from dark matter annihilation or decay. In the absence of a robustdark matter signal, constraints are presented. We consider both gamma rays produced directly in the dark matterannihilation/decay and produced by inverse Compton scattering of the e+/e- produced in the annihilation/decay.Conservative limits are derived requiring that the dark matter signal does not exceed the observed diffuse gamma-rayemission. A second set of more stringent limits is derived based on modeling the foreground astrophysical diffuseemission using the GALPROP code. Uncertainties in the height of the diffusive cosmic-ray halo, the distributionof the cosmic-ray sources in the Galaxy, the index of the injection cosmic-ray electron spectrum, and the columndensity of the interstellar gas are taken into account using a profile likelihood formalism, while the parametersgoverning the cosmic-ray propagation have been derived from fits to local cosmic-ray data. The resulting limitsimpact the range of particle masses over which dark matter thermal production in the early universe is possible, andchallenge the interpretation of the PAMELA/Fermi-LAT cosmic ray anomalies as the annihilation of dark matter.

[发布日期] 2012-12-20

[学科分类] 天体物理学