High-energy neutrino signatures of dark matter

It has been suggested that the excesses of high-energy cosmic ray electrons and positrons seen by PAMELA and the Fermi Gamma Ray Space Telescope are evidence of dark matter annihilation or decay in the Galactic halo. To accommodate these signals however, the final states must be predominantly muons or taus. These leptonic final states will produce neutrinos, which are potentially detectable with the IceCube neutrino observatory. We find that with five years of data, IceCube (supplemented by DeepCore) can significantly constrain the relevant parameter space for both annihilating or decaying dark matter, and may be capable of discovering leptophilic dark matter in the halo of the Milky Way.

Figure 1

Reach of ICECUBE/DeepCore to neutrinos from DM annihilation to ${\mu }^{+}{\mu }^{-}$. Shown are the $5\sigma$ (dashed line) detection and the $2\sigma$ limit (solid line) on the boost factor as a function of WIMP mass after 5 years of operation. Also shown are the $2\sigma$ contours in the boost factor $B$ as function of DM mass for Fermi (dotted line) and PAMELA (dot-dashed line) inferred from 11 for $(\chi \chi \to {\mu }^{+}{\mu }^{-})$.

Figure 2

Exclusion limits in the dark matter lifetime versus mass plane, for decays to ${\mu }^{+}{\mu }^{-}$, ${\tau }^{+}{\tau }^{-}$, and ${\mu }^{+}{\mu }^{-}{\mu }^{+}{\mu }^{-}$. The green region is preferred by the observations of PAMELA, light red is preferred by FGST, and the dark red region is preferred by the combination of these measurements. The blue line labeled “$2\sigma$” is the projected $2\sigma$ limit for 5-years of running at IceCube/DeepCore, while the red “$5\sigma$” line is the $5\sigma$ discovery reach. For details of the other bounds displayed, see text. Our results (blue $2\sigma$ and red $5\sigma$ lines from IceCube/DeepCore) have been superimposed upon a plot taken from Ref. 27 with permission of the authors.