Testing structure formation in the universe via coupled matter fluids

Abstract

We present results from a new framework in which the matter fluid is split into a strongly clustered “halo” component and a weakly clustered “free” component accreted by the haloes. The interaction is modelled using a simple function of the matter density that mimics recently published results from halo theory of N-body simulations. We find that whereas the background dynamics are consistent with the standard non-interacting case, the density perturbations are highly sensitive to the energy-momentum transfer, with our model approaching the standard ΛCDM cosmology today.