Abstract
With the observation of high-energy astrophysical neutrinos by the IceCube Neutrino Observatory, interest has risen in models of PeV-mass decaying dark matter particles to explain the observed flux. We present two dedicated experimental analyses to test this hypothesis. One analysis uses 6 years of IceCube data focusing on muon neutrino ‘track’ events from the Northern Hemisphere, while the second analysis uses 2 years of ‘cascade’ events from the full sky. Known background components and the hypothetical flux from unstable dark matter are fitted to the experimental data. Since no significant excess is observed in either analysis, lower limits on the lifetime of dark matter particles are derived: we obtain the strongest constraint to date, excluding lifetimes shorter than 10^{28}hbox { s} at 90% CL for dark matter masses above 10~hbox {TeV}.
Highlights
We present two dedicated analyses to test whether the description of the observed neutrino flux can be improved by an additional component from heavy dark matter decays as an alternative to bottom-up scenarios of astrophysical acceleration [33]
Our results significantly improve upon the best previous experimental bounds on decaying dark matter obtained with gamma rays [44,45,46,47], neutrinos [48], and those derived from high-energy cosmic rays and the cosmic microwave background radiation [4,5]
Two analyses on statistically independent datasets searching for a contribution from decaying dark matter to the astrophysical neutrino flux have been presented
Summary
The origin of the flux of high-energy neutrinos discovered by IceCube [1,2] remains unidentified [3]. We present two dedicated analyses to test whether the description of the observed neutrino flux can be improved by an additional component from heavy (mDM > 10 TeV) dark matter decays as an alternative to bottom-up scenarios of astrophysical acceleration [33] Such heavy particles are receiving increased attention because the classic WIMP paradigm of weak-scale mass dark matter is disfavoured by the negative results in searches for new physics at the LHC [34], in direct DM detection experiments [35,36,37,38,39], and in searches for DM annihilation into neutrinos [40,41] or gamma-rays [42,43,44,45,46]. The two analysis samples are statistically independent, and while the track sample contains a much larger number of events, the full-sky coverage and better energy resolution of the cascade sample (see Table 1) lead to comparable sensitivities
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