Decaying dark matter at IceCube and its signature on High Energy gamma experiments

Abstract

The origin of neutrino flux observed in IceCube is still mainly unknown. Typically two flux components are assumed, namely: atmospheric neutrinos and an unknown astrophysical term. In principle the latter could also contain a top-down contribution coming for example from decaying dark matter. In this case one should also expect prompt and secondary gamma's as well. This leads to the possibility of a multimessenger analysis based on the simultaneous comparison of the Dark Matter hypothesis both with neutrino and high energy gamma rays data. In this paper, we analyze, for different decaying Dark Matter channels, the 7.5 years IceCube HESE data, and compare the results with previous exclusion limits coming from Fermi data. Finally, we test whether the Dark Matter hypothesis could be further scrutinised by using forthcoming high energy gamma rays experiments. * m.chianese@uva.nl † dfgfiorillo@na.infn.it ‡ miele@na.infn.it § smorisi@na.infn.t ¶ a hard isotropic extragalactic neutrino flux and an additional softer one with a potential galactic origin [27][28][29][30][31][32][33]. This two-component hypothesis is at the same time supported by the first combined analysis of IceCube and ANTARES data [34]. It turns out that both IceCube and ANTARES telescopes have measured in the same energy range (about 40-200 TeV) a slight excess with respect to an astrophysical power-law flux deduced by TG data (γ ≤ 2.2), after the background subtraction [34][35][36][37].An alternative source for this diffuse UHE neutrino flux is decaying Dark Matter (DM) . While another available source might be identified with annihilating DM [33,35,39,[63][64][65][66][67], the unitarity limit leads in general to small neutrinos fluxes which are therefore not detectable. Bounds are available in previous studies both for decaying [68,69] and annihilating DM [70,71]. Analyses mainly devoted to the neutrino energy spectrum are able to distinguish among different DM decay channels. Moreover, different DM models are further constrained through the informations coming from gamma-ray observations. The current data (neutrinos and gamma-rays) show that hadronic final states are strongly disfavored or excluded, while leptonic ones are slightly disfavored or allowed [72]. The most favorable case is a heavy DM candidate coupled only to neutrinos.The foregoing observations have shown that gamma-rays constraints, mainly coming from observations of the Fermi-LAT experiment, have been critical in excluding or disfavoring various DM decay channels. It is therefore all the more interesting to find out whether gamma-rays experiments in different energy ranges would be able to put further constraints on the existence of decaying DM fluxes. While the lower energy range (up to few hundreds GeV) is mainly explored by Fermi LAT [73], the higher energy range (from about 100 TeV) is explored by air shower experiments [74] and has already been used in exploring constraints on annihilating or decaying Dark Matter through data by Pierre Auger [75], CASA-MIA [76] and KASCADE [77];...

Dark matter spectra from the electroweak to the Planck scale

“…Independent of UV motivations, there is a clear reason to consider searching for such DM: the robust experimental program to probe astrophysical messengers at higher energies. Many instruments can probe heavy DM, including HAWC [32], IceCube [5,[33][34][35][36][37][38], ANTARES [39,40], Pierre Auger Observatory [41][42][43][44], Telescope Array [45,46], and in the future CTA [47,48], LHAASO [49,50], IceCube-Gen2 [51], and KM3NET [52,53]. Taken together, these experiments demonstrate that in the coming years we will continue to probe the universe at higher energies and to greater sensitivities.…”

Interpreting the high-energy neutrino sky through an angular power spectrum analysis

“…We extend the analysis to masses at lower energies up to 100 GeV for annihilating DM, and find that even at lower energies, the APS analysis offers a robust way to interpret the neutrino sky [13]. Both instruments will be sensitive to the present 7.5-year HESE best-fit of the decaying DM component [14], shown with a black stars in the figure . As the APS analysis relies on angular information only, it is robust against any degeneracies in the neutrino energy spectrum expected from astrophysical sources as well as in DM particles.…”

Constraints on the models of the origin of high-energy astrophysical neutrinos

“…In the context of explaining the IceCube results, this scenario has been discussed in particular in Refs. [255][256][257][258][259][260]. The entire observed neutrino spectrum from tens of TeV to tens of PeV cannot be explained in this way, because the energy distribution of the decay products is noticeably narrower, but this mechanism can explain the observed flux at some energies.…”