Confusing the extragalactic neutrino flux limit with a neutrino propagation limit

Abstract

We study the possible suppression of theextragalactic neutrino flux due to a nonstandard interaction duringits propagation. In particular, we study neutrino interaction withan ultra-light scalar field dark matter. It is shown that theextragalactic neutrino flux may be suppressed by such aninteraction, leading to a new mechanism to reduce the ultra-highenergy neutrino flux. We study both the cases of non-self-conjugateas well as self-conjugate dark matter. In the first case, thesuppression is independent of the neutrino and dark mattermasses. We conclude that care must be taken when explaining limitson the neutrino flux through source acceleration mechanisms only,since there could be other mechanisms for the reduction of theneutrino flux.