Constraints on neutrino-dark matter interactions from cosmic microwave background and large scale structure data

We update a previous investigation of cosmological effects of a nonstandard interaction between neutrinos and dark matter. Parametrizing the elastic-scattering cross section between the two species as a function of the temperature of the Universe, the resulting neutrino-dark matter fluid has a nonzero pressure, which determines diffusion-damped oscillations in the matter power spectrum similar to the acoustic oscillations generated by the photon-baryon fluid. Using cosmic microwave background data in combination with large scale structure experiment results, we then put constraints on the fraction of the interacting dark matter component as well as on the corresponding opacity.