Confusing the extragalactic neutrino flux limit with a neutrino propagation limit

TL;DR

This paper investigates how interactions with ultra-light scalar dark matter could suppress the extragalactic neutrino flux during propagation, challenging the interpretation of neutrino flux limits based solely on source acceleration.

Contribution

It introduces a novel mechanism where neutrino-dark matter interactions can reduce the observed neutrino flux, highlighting the need to consider propagation effects in flux limit analyses.

Findings

Neutrino flux can be suppressed by interactions with ultra-light scalar dark matter.

Suppression is independent of neutrino and dark matter masses in certain cases.

Propagation effects can mimic or enhance flux suppression beyond source mechanisms.

Abstract

We study the possible suppression of the extragalactic neutrino flux due to a nonstandard interaction during its propagation. In particular, we study neutrino interaction with an ultra-light scalar field dark matter. It is shown that the extragalactic neutrino flux may be suppressed by such an interaction, leading to a new mechanism to reduce the ultra-high energy neutrino flux. We study both the cases of non-self-conjugate as well as self-conjugate dark matter. In the first case, the suppression is independent of the neutrino and dark matter masses. We conclude that care must be taken when explaining limits on the neutrino flux through source acceleration mechanisms only, since there could be other mechanisms for the reduction of the neutrino flux.