1 research outputs found
Constraints on the Galactic Halo Dark Matter from Fermi-LAT Diffuse Measurements
We have performed an analysis of the diffuse gamma-ray emission with the Fermi Large Area Telescope (LAT) in
the Milky Way halo region, searching for a signal from dark matter annihilation or decay. In the absence of a robust
dark matter signal, constraints are presented. We consider both gamma rays produced directly in the dark matter
annihilation/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-ray
emission. A second set of more stringent limits is derived based on modeling the foreground astrophysical diffuse
emission using the GALPROP code. Uncertainties in the height of the diffusive cosmic-ray halo, the distribution
of the cosmic-ray sources in the Galaxy, the index of the injection cosmic-ray electron spectrum, and the column
density of the interstellar gas are taken into account using a profile likelihood formalism, while the parameters
governing the cosmic-ray propagation have been derived from fits to local cosmic-ray data. The resulting limits
impact the range of particle masses over which dark matter thermal production in the early universe is possible, and
challenge the interpretation of the PAMELA/Fermi-LAT cosmic ray anomalies as the annihilation of dark matter