Cosmic-Ray Boosted Relic Neutrinos

The cosmic neutrino background is a prediction of standard cosmology but remains undetected due to the extremely low energies involved. By elastic scattering on cosmic-ray nuclei, these relic neutrinos can be upscattered to ultra-high energies observable by current neutrino telescopes such as the IceCube Neutrino Observatory and the Pierre Auger Observatory. Earlier calculations only took into account the elastic scattering on the proton component and ignored the effect of coherent elastic neutrino-nucleus scattering on heavier nuclei. In this contribution, we study the flux of cosmic-ray-boosted relic neutrinos, including coherent scattering on nuclei, and use the current upper limits to constrain the cosmic neutrino background density.