Multiwavelength signals of dark matter annihilations at the Galactic center

Abstract

We perform a systematic study of the multiwavelength signal induced by weakly interacting massive particle (WIMP) annihilations at the Galactic Center (GC). Referring to a generic WIMP dark matter (DM) scenario and depending on astrophysical inputs, we discuss spectral and angular features and sketch correlations among signals in the different energy bands. None of the components which have been associated to the GC source Sgr ${\mathrm{A}}^{*}$, nor the diffuse emission components from the GC region, have spectral or angular features typical of a DM source. Still, data sets at all energy bands, namely, the radio, near-infrared, x-ray and gamma-ray bands, contribute to place significant constraints on the WIMP parameter space. In general, the gamma-ray energy range is not the one with the largest signal to background ratio. In the case of large magnetic fields close to the GC, x-ray data give the tightest bounds. The emission in the radio band, which is less model dependent, is very constraining as well. The recent detection by HESS of a GC gamma-ray source, and of a diffuse gamma-ray component, limits the possibility of a DM discovery with the next generation of gamma-ray telescopes, like GLAST and CTA. We find that most of the region in the parameter space accessible to these instruments is actually already excluded at other wavelengths. On the other hand, there may be still an open window to improve constraints with wide-field radio observations.