Testing the Interaction Between Baryons and Dark Energy with Recent Cosmological Observations

Abstract

We study a modified interacting dark energy (MIDE) model as a candidate to describe possible interaction between dark energy and dark matter as well as that between dark energy and baryonic matter. More specifically, we introduce a new parameter γ b to quantify the extent of interaction between dark energy and baryons. With three classes of cosmological distance observations including CMB measurements from Planck and WMAP9 results, as well as the recent direct measurements of the Hubble parameter as a function of redshift, we study the allowable values of γ c and γ b and other cosmological parameters. The constraint results obtained by using the MCMC method show: (1) The interaction term γ b quantifying the extent of interaction between baryonic matter and dark energy is nearly equal to 0, which strongly support the whole coupled dark energy scenario based on the assumption that baryons should remain uncoupled in order to allow a non-negligible coupling to dark matter. (2) At the 95.4 % confidence level, we see the energy of dark energy is slightly transferring to that of dark matter; (3) Concerning the typical value of the present energy density ratio between baryonic matter and dark matter in the universe, we obtain a positive coupling between dark energy and matter at 2σ, which indicates that dark energy is leaking energy to matter. Finally, concerning the observational density parameter ratio Ω b /Ω m derived from the gas mass fraction data (f g a s ), within the framework of the phenomenological interaction model, we observe a good compatibility between the observational constraints from f g a s and other combined data.