Conservative Constraints on dark matter annihilation into gamma rays

Using gamma-ray data from observations of the Milky Way, Andromeda (M31), and the cosmic background, we calculate conservative upper limits on the dark matter self-annihilation cross section to monoenergetic gamma rays, _{gamma gamma}, over a wide range of dark matter masses. We focus on the gamma gamma final state, as it would be a very clean signature of dark matter annihilation. As our constraints on the cross section are affected by astrophysical uncertainties, we are conservative in our input choices and analysis methods and show how our results depend on these. Using our upper limits on the dark matter annihilation cross section to gamma rays, and a conservative assumption about the branching ratio to monoenergetic gamma rays, we define upper limits on the total cross section and compare to other constraints.