Dark Matter Interpretation of Recent Electron and Positron Data

We analyze the recently released Fermi-LAT data on the sum of electrons and positrons. Compared to a conventional, pre-Fermi, background model, a surprising excess in the several hundred GeV range is found and here we analyze it in terms of dark matter models. We also compare with newly published results from PAMELA and H.E.S.S., and find models giving very good fits to these data sets as well. If this dark matter interpretation is correct, we also predict the possibility of a sharp break in the diffuse gamma-ray spectrum coming from final state radiation.

Figure 1

The $2\sigma$ contours in the enhancement factor—mass plane for (a) annihilation to ${\mu }^{+}{\mu }^{-}$, (b) the Nomura-Thaler–type model N3, and (c) the Arkani-Hamed et al.–type model AH4. The contours are shown for PAMELA and Fermi, whereas the H.E.S.S. data are used only as an upper limit. The black dot is the example model shown in Fig. 2.

Figure 2

Spectra for examples of good fit models in 1. The signal and background are shown for electrons ($e^{+}+e^{-}$) together with Fermi [9] and H.E.S.S. data [11, 29]. The H.E.S.S. data and the background model have been rescaled with a factor 0.85. In the inset, the positron fraction as measured with PAMELA is shown together with the predicted signal for the same model.