Probing dark matter signals in neutrino telescopes through angular power spectrum

Abstract

The hypothesis of two different components in the high-energy neutrino flux observed with IceCube has been proposed to solve the tension among different data-sets and to account for an excess of neutrino events at 100 TeV . In addition to a standard astrophysical power-law component, the second component might be explained by a different class of astrophysical sources, or more intriguingly, might originate from decaying or annihilating dark matter. These two scenarios can be distinguished thanks to the different expected angular distributions of neutrino events. Neutrino signals from dark matter are indeed expected to have some correlation with the extended galactic dark matter halo. In this paper, we perform angular power spectrum analyses of simulated neutrino sky maps to investigate the two-component hypothesis with a contribution from dark matter. We provide current constraints and expected sensitivity to dark matter parameters for future neutrino telescopes such as IceCube-Gen2 and KM3NeT. The latter is found to be more sensitive than IceCube-Gen2 to look for a dark matter signal at low energies towards the galactic center. Finally, we show that after 10 years of data-taking, they will firmly probe the current best-fit scenario for decaying dark matter by exploiting the angular information only.

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

“…It is also convenient to search for such anisotropy, sensitive to the details of the source distribution, in the data with nonparametric tests [54]. Recently, experimental data analyses have used this approach in the context of particular dark-matter models [56,57] together with the analysis of the contribution of dark matter to the observed neutrino spectrum [58,59]. Increas- Bold curves -the best fit from IceCube cascade events [51], thin curves -the strongest upper limits (90% CL) from the joint analysis of IceCube and ANTARES [52] (solid lines -KRAγ with cosmic-ray cutoff at 50 PeV, dotted -at 5 PeV).…”

Dark Matter Phenomenology from Upcoming Neutrino Telescopes:

“…We employ an angular power spectrum (APS) analysis described in Refs. [8,9] where the anisotropy of the expected dark matter signal coming from the Galactic center is exploited in order to distinguish against the approximately isotropic astrophysical and atmospheric backgrounds. Our analysis extends to a lower energy region from that in ref.…”

“…Our analysis extends to a lower energy region from that in ref. [9], which limited its study to DM ≥ 200 TeV, here our projections start at DM = 200 GeV. In this energy region, the background neutrino fluxes that dominate are from atmospheric neutrinos.…”

“…The projections for KM3NeT that we calculated are not necessarily the most optimistic as such limits are often analysis dependent. This is because we opted to employ an angular power spectrum (APS) analysis [8,9], which is remarkably robust against changes in the dark matter density profile. This of course comes at a cost, and we anticipate with a different analysis, projections assuming a profile which is denser in the centre of the Galaxy, could be more sensitive.…”

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

“…[8], however, we test different DM characteristics in Ref. [9] as well. The bands represent the median and upper 95% values of the MC runs, constrained at -value of 0.05.…”