New limits on coupled dark energy model after Planck 2015

Abstract

Abstract We used the Planck 2015 cosmic microwave background anisotropy, baryon acoustic oscillation, type-Ia supernovae, redshift-space distortions, and weak gravitational lensing to test the model parameter space of coupled dark energy. We assumed the constant and time-varying equation of state parameter for dark energy, and treated dark matter and dark energy as the fluids whose energy transfer was proportional to the combined term of the energy densities and equation of state, such as Q = 3 H ξ ( 1 + w x ) ρ x and Q = 3 H ξ [ 1 + w 0 + w 1 ( 1 − a ) ] ρ x , the full space of equation of state could be measured when we considered the term ( 1 + w x ) in the energy exchange. According to the joint observational constraint, the results showed that w x = − 1 . 00 6 − 0 . 027 + 0 . 047 and ξ = 0 . 09 8 − 0 . 098 + 0 . 026 for coupled dark energy with a constant equation of state, w 0 = − 1 . 07 6 − 0 . 076 + 0 . 085 , w 1 = − 0 . 06 9 − 0 . 319 + 0 . 361 , and ξ = 0 . 21 0 − 0 . 210 + 0 . 048 for a variable equation of state. We did not get any clear evidence for the coupling in the dark fluids at 1 σ region.