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Register a new userA dark matter interpretation for the ARCADE excess?
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The ARCADE 2 Collaboration has recently measured an isotropic radio emission which is significantly brighter than the expected contributions from known extra-galactic sources. The simplest explanation of such excess involves a new population of unresolved sources which become the most numerous at very low (observationally unreached) brightness. We investigate this scenario in terms of synchrotron radiation induced by WIMP annihilations or decays in extragalactic halos. Intriguingly, for light-mass WIMPs with thermal annihilation cross-section, and fairly conservative clustering assumptions, the level of expected radio emission matches the ARCADE observations.
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The 2-years MESE IceCube events show a slightly excess in the energy range 10-100 TeV with a maximum local statistical significance of 2.3$sigma$, once a hard astrophysical power-law is assumed. A spectral index smaller than 2.2 is indeed suggested by multi-messenger studies related to $p$-$p$ sources and by the recent IceCube analysis regarding 6-years up-going muon neutrinos. In the present paper, we propose a two-components scenario where the extraterrestrial neutrinos are explained in terms of an astrophysical power-law and a Dark Matter signal. We consider both decaying and annihilating Dark Matter candidates with different final states (quarks and leptons) and different halo density profiles. We perform a likelihood-ratio analysis that provides a statistical significance up to 3.9$sigma$ for a Dark Matter interpretation of the IceCube low energy excess.
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