Current and future constraints on dark matter from prompt and inverse-Compton photon emission in the isotropic diffuse gamma-ray background

We perform a detailed examination of current constraints on annihilating and decaying dark matter models from both prompt and inverse-Compton emission photons, including both model-dependent and model-independent bounds. We also show that the observed isotropic diffuse gamma-ray background (DGRB), which provides one of the most conservative constraints on models of annihilating weak-scale dark matter particles, may enhance its sensitivity by a factor of 2 to 3 (95% C. L. ) as the Fermi-LAT experiment resolves DGRB contributing blazar sources with five years of observation. For our forecasts, we employ the results of constraints to the luminosity-dependent density evolution plus blazar spectral energy distribution sequence model, which is constrained by the DGRB and blazar source count distribution function.