Upper bounds on signals due to WIMP self--annihilation: comments on the case of the synchrotron radiation from the galactic center and the WMAP haze

Abstract

Two recent papers reconsider the possibility that the excess of microwave emission from a region within $\sim 20^0$ of the galactic center (the {\it WMAP haze}), measured by WMAP, can be due to the synchrotron emission originated by neutralino self-annihilation; on the basis of this possible occurrence, also upper bounds on the neutralino self-annihilation cross--section are suggested. In the present note, we show that in the common case of thermal WIMPs in a standard cosmological model, when the rescaling of the galactic WIMP density is duly taken into account for subdominant WIMPs, the upper bound applicable generically to {\it any} signal due to self-conjugate WIMPs is more stringent than the ones obtained from analysis of the WMAP haze. We also argue that an experimental upper bound, which can compete with our generic upper limit, can rather be derived from measurements of cosmic antiproton fluxes, for some values of the parameters of the astrophysical propagation model. Finally, we comment on the possible impact of our generic upper bound on the interpretation of the WMAP haze in terms of thermal neutralinos in a standard cosmological scheme.

arXiv comment3 pages, comments and 1 figure added

References in corpus (10)

• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Antiprotons in cosmic rays from neutralino annihilation
• Precision Measurement of Cosmic-Ray Antiproton Spectrum
• Antiprotons from spallations of cosmic rays on interstellar matter
• Small-scale clumps in the galactic halo and dark matter annihilation
• Evidence Of Dark Matter Annihilations In The WMAP Haze
• Successive Measurements of Cosmic-Ray Antiproton Spectrum in a Positive Phase of the Solar Cycle
• Indirect signals from light neutralinos in supersymmetric models without gaugino mass unification
• Antiproton fluxes from light neutralinos

Cited by in corpus (7)

• Interpreting the recent results on direct search for dark matter particles in terms of relic neutralino
• Antideuteron fluxes from dark matter annihilation in diffusion models
• WMAP Haze: Directly Observing Dark Matter?
• Astrophysical limits on light NMSSM neutralinos
• Evolution of Dark Matter Halos and their Radio Emissions
• Enlarging mSUGRA parameter space by decreasing pre-BBN Hubble rate in Scalar-Tensor Cosmologies
• The Morphology of the Galactic Dark Matter Synchrotron Emission with Self-Consistent Cosmic Ray Diffusion Models