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 quasi-cusps, -kinks, 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, the spectrum of cosmic string neutrinos does not match that of the observed HEAN spectrum. We thus find that the maximum contribution of cosmic string neutrinos, through these two scenarios, to be at most $\sim 45$ % of the observed flux. However, we also find that the presence of cosmic string neutrinos can lead to bumps in the observed neutrino spectrum. Finally, for each of the models presented, we present the viable parameter space for neutrino emission.
Comment: 11 pages, 7 figures