Cosmological model of the interaction between dark matter and dark energy

¹ School of Astronomy and Space Science, Nanjing University, Nanjing 210093, PR China
² Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, PR China
e-mail: fayinwang@nju.edu.cn

Received: 4 September 2013
Accepted: 16 March 2014

Abstract

We tested a cosmological model for the interaction between dark matter and dark energy with a dynamic equation of state w_DE(z) = w₀ + w₁z/ (1 + z), using type Ia supernovae (SNe Ia), Hubble parameter data, baryonic acoustic oscillation (BAO) measurements, and cosmic microwave background (CMB) observations. This interacting cosmological model has not been studied before. The best-fit parameters with 1σ uncertainties are δ = − 0.022 ± 0.006, Ω⁰_DM = 0.213 ± 0.008, w₀ = − 1.210 ± 0.033 and w₁ = 0.872 ± 0.072 with χ²_min/d.o.f. = 0.990. At the 1σ confidence level, we find δ < 0, which means that the energy transfer prefer ably occurring from dark matter to dark energy. We also find that the SNe Ia data disagree with the combined CMB, BAO, and Hubble parameter data. The evolution of ρ_DM/ρ_DE indicates that this interacting model is a good approach to solve the coincidence problem, because ρ_DE decreases with scale factor a. The transition redshift is z_tr = 0.63 ± 0.07 in this model.