Detecting the Cosmic Neutrino Background with Multi-Messenger Signatures

The Cosmic Neutrino Background (CnuB) is the oldest relic population of Standard Model particles in the Universe, carrying information from roughly one second after the Big Bang. Its detection would mark a major milestone for both cosmology and astro-particle physics. Here I will discuss a promising detection strategy relying on the scattering of cosmic rays off CnuB neutrinos over cosmological distances, inducing a flux of relic neutrinos boosted to high energies. This boosted CnuB component can extend into the energy range accessible to neutrino telescopes such as IceCube and next-generation detectors. I will assess the feasibility of this scenario in some detail, identifying the astrophysical and experimental conditions under which future ultra-high-energy neutrino telescopes could detect the CnuB and distinguish its signal from the cosmogenic neutrino background. I will also discuss a complementary channel based on gamma rays associated with these scattering processes. Finally, I will show how the detection of an enhanced cosmological CnuB density could reveal that neutrinos comprise the dominant dark matter content of the Universe.