Searching for Dark Matter in the CMB: A Compact Parameterization of Energy Injection from New Physics
Douglas P. Finkbeiner, Silvia Galli, Tongyan Lin, & Tracy R. Slatyer 2011

High-precision measurements of the temperature and polarization anisotropies of the cosmic microwave background radiation have been employed to set robust constraints on dark matter annihilation during recombination. In this work we improve and generalize these constraints to apply to energy injections during the recombination era with arbitrary redshift dependence. Our approach also provides more rigorous and model-independent bounds on dark matter annihilation and decay scenarios. We employ principal component analysis to identify a basis of weighting functions for the energy injection. The coefficients of these weighting functions parameterize any energy injection model and can be constrained directly by experiment. For energy injections that are currently allowed by \WMAP7 data, up to 3 principal component coefficients are measurable by Planck and up to 6 coefficients are measurable by an ideal cosmic variance limited experiment. We also compute the biases to the other cosmological parameters from these generalized energy injections.