γ rays from neutralino annihilation

We calculate the flux of cosmic γ rays expected from the annihilation of neutralinos in the galactic halo. Our calculation of the annihilation cross section to two photons improves the existing calculations by inclusion of exact one-loop diagrams for the amplitudes involving Higgs boson and chargino states as well as those involving fermion and sfermion states. A survey of supersymmetric parameter space shows that numerous models would be observable at the 3σ level with an air Cherenkov telescope with an exposure of ${10}^4$ ${\mathrm{m}}^2$ yr.