Cosmic neutrinos and gravity

We explore the potential of neutrino flavour oscillations to constrain and probe new physics models in various settings. First, we show that a coupling between an axion like dark matter candidate and a sterile neutrino with altered dispersion relations can be used to reconcile the sterile flavour with cosmological bounds. The allowed model parameter space is determined by comparing the predicted values for a set of central quantities to those extracted from experiment. Moreover, we discuss how astrophysical and atmospheric neutrinos can be utilised to probe effective low energy models of quantum gravity. We propose that if quantum gravity violates global quantum numbers, neutrino oscillations provide new possibilities to study the hypothetical fermionic dark sector. We perform a thorough statistical analysis to estimate the sensitivity of atmospheric oscillation experiments, like IceCube, to the considered class of models. Finally, we discuss potential effects of classical gravity on the neutrino flavour dynamics and the respective implications for current and near-future neutrino experiments. In the course of this, we derive a formula for the amplitude of neutrino flavour transitions in curved spacetimes.