Cosmic Acceleration from a Two-Component Dark Matter Superfluid

Abstract

We investigate the cosmological implications of a two-component dark matter superfluid as proposed by Ferreira et al. (2019). Through contact interactions between the axion-like particles in these components, a late-time potential dominates the energy content of the universe and leads to vacuum energy-like accelerated expansion. We test this model in three ways: by evolving the Hubble parameter to very late-times, by comparing the luminosity distance to type 1a supernova observations, and by comparing theoretical values of the CMB shift parameter and dark matter density parameter to those from WMAP. In terms of the Hubble parameter, we find that it is similar to $\Lambda$CDM from the surface of last scattering until the present when the interaction potential causes a significant difference. We find that the luminosity distances predicted by the model agree with supernova distance moduli for z < 1.3 for a certain range of energy gaps between the two superfluid states. Finally, given accepted CMB shift parameter values, we derive constraints on the dark matter density parameter Ωm = .255±.035, which agrees with that from SDSS-II/SNLS results of Ωm = .295±.035.