Attenuation of the ultra-high-energy neutrino flux by dark matter scatterings

A flux of ultra-high-energy (UHE) neutrinos is generally expected to be produced by astrophysical sources at cosmological distances and to reach Earth. In this paper, we investigate the impact of neutrino scattering with dark matter (DM) particles in both the intergalactic medium and the Milky Way on the total flux, energy spectrum, and arrival directions of UHE neutrinos. We emphasize the complementarity of neutrino detectors at different latitudes to probe the anisotropy in the flux at Earth due to the attenuation of the neutrino flux in the Milky Way dark matter halo. We also discuss that, with mild astrophysical assumptions, limits on the DM-$ν$ scattering cross section can be placed even if the neutrino sources are unknown. Finally, we explore all this phenomenology with the recent UHE neutrino event KM3230213A, and place the corresponding limits in the DM-$ν$ scattering cross-section.