Extragalactic neutrinos as tracers of dark matter?

Abstract

Neutrinos produced in extragalactic sources may experience flavor-oscillations and decoherence on their way to Earth due to their interaction with dark matter (DM). As a result, they may be detected in pointer-states other than the flavor states produced at the source. The oscillation pattern and the structure of the pointer-states can give us information on the characteristics of the DM and the kind of interaction that has taken place. From this perspective, neutrinos can be viewed as DM-tracers. We study the local evolution of neutrino flavor-eigenstates due to local effects produced by the presence of DM. To explore the sensitivity of the model, we consider different DM density profiles, masses and interactions. Starting from the eigenstates of the neutrino mass Hamiltonian, we construct flavor-states with the neutrino mixing-matrix in vacuum. We then include local interactions with DM, acting along the neutrino path towards the Earth, and analyze the resulting probabilities. In doing so, we adopt different DM density profiles, e.g. a constant, a local isotropic, and a Navarro?Frenk?White density distribution. Finally, by following the time-evolution of the flavor-states, we identify pointer-states and interpret the results in terms of the adopted DM model. In addition, neutrinos may experience changes in the oscillation parameters and resonances (MSW effect), the extent of which depends on the DM density profile. Thus, the presence of DM may enhance or suppress the oscillation pattern. The suppression of components of the neutrino wave-packet (decoherence effects) may also take place. The features of the calculated response seem to support the notion that these neutrinos can be taken as DM tracers. From a theoretical point of view, the coexistence and/or competition of decoherence and matter effects is sustained by the results.