High-energy astrophysical neutrinos from cosmic strings

Cosmic strings that couple to neutrinos may account for a portion of the high-energy astrophysical neutrino (HEAN) flux seen by IceCube. Here, we calculate the observed spectrum of neutrinos emitted from a population of cosmic-string loops that contain quasicusps, quasikinks, or kink-kink collisions. We consider two broad neutrino emission models: one where these string features emit a neutrino directly, and one where they emit a scalar particle which then eventually decays to a neutrino. In either case, we find the spectrum of cosmic-string neutrinos to follow a two-parameter model described by a power law with a high-energy cutoff. While none of the models in question fully match the observed HEAN spectrum, we do find that the maximum contribution of cosmic-string neutrinos can still be an O(1) fraction of the observed flux in addition to producing a bump in the observed neutrino spectrum. Finally, for each of the models presented, we present the viable parameter space for neutrino emission.

Automated summary

In this study, we investigate the coupling between cosmic strings and neutrinos, suggesting that cosmic strings may contribute to the high-energy astrophysical neutrino flux observed by IceCube. By calculating the neutrino spectrum emitted from cosmic string loops with quasicusps, quasikinks, or kink-kink collisions, we consider two models of neutrino emission: one where the string features directly emit neutrinos, and one where they emit a scalar particle that eventually decays into neutrinos. In either case, we find that the spectrum of cosmic string neutrinos can be described by a power law with a high-energy cutoff. Although none of the models fully match the observed high-energy neutrino spectrum, we find that the maximum contribution of cosmic string neutrinos can still be a significant fraction of the observed flux, causing a bump in the observed neutrino spectrum. Finally, we present the viable parameter space for neutrino emission in each of the models.