  The possible effect on the flavour spectra of astronomical neutrinos from a
neutrino-dark matter interaction has been investigated for decoherent
neutrinos. In this work, we report results calculated for coherent neutrinos.
This was done with two different models for the neutrino dark-matter
interactions: a flavour state interaction,as for the weak interaction in the
Standard Model, and a mass state interaction, which is predicted by certain
non-Standard Models (specifically Scotogenic models). It was found that using a
coherent analysis dramatically increased the explorable parameter space for the
neutrino-dark matter interaction. However, the detection of coherent
astronomical neutrinos presents a significant challenge to experimentalists,
because such a detection would require an improvement in energy resolution by
at least six orders of magnitude, with similar improvements in astronomical
distance determinations.
