Cosmological model of the interaction between dark matter and dark energy

TL;DR

The paper investigates a cosmological model in which dark matter and dark energy exchange energy via a constant coupling $\delta$ and a dynamic dark-energy equation of state $w_{DE}(z)=w_{0}+w_{1}\frac{z}{1+z}$. Constraining the model with Union 2.1 SNe Ia, Hubble parameter measurements, BAO, and WMAP9 distance priors yields best-fit parameters $\delta=-0.022\pm0.006$, $\Omega_{DM}^{0}=0.213\pm0.008$, $w_{0}=-1.210\pm0.033$, and $w_{1}=0.872\pm0.072$ with $\chi^{2}_{min}/dof=0.990$. The results indicate energy transfer from dark matter to dark energy and reveal a tension between SNe Ia and the combined CMB/BAO/H(z) data. The model slows the evolution of $\rho_{DM}/\rho_{DE}$ relative to $\Lambda$CDM, addressing the coincidence problem, and finds a transition redshift $z_{tr}=0.63\pm0.07$, though the assumption of a constant $\delta$ leads to rapid early-time DE evolution, suggesting $\delta(a)$ may vary in a more complete description.

Abstract

In this paper, we test the dark matter-dark energy interacting cosmological model with a dynamic equation of state $w_{DE}(z)=w_{0}+w_{1}z/(1+z)$, using type Ia supernovae (SNe Ia), Hubble parameter data, baryonic acoustic oscillation (BAO) measurements, and the cosmic microwave background (CMB) observation. This interacting cosmological model has not been studied before. The best-fitted parameters with $1 σ$ uncertainties are $δ=-0.022 \pm 0.006$, $Ω_{DM}^{0}=0.213 \pm 0.008$, $w_0 =-1.210 \pm 0.033$ and $w_1=0.872 \pm 0.072$ with $χ^2_{min}/dof = 0.990$. At the $1 σ$ confidence level, we find $δ<0$, which means that the energy transfer prefers from dark matter to dark energy. We also find that the SNe Ia are in tension with the combination of 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 the $ρ_{DE}$ decrease with scale factor $a$. The transition redshift is $z_{tr}=0.63 \pm 0.07$ in this model.

Figures (6)

• Figure 1: The $\delta - \Omega_{DM}$ contours with different data combinations: SNe (gray and light gray contours), SNe + BAO (red and pink contours), SNe + CMB (blue and light purple contours), CMB + BAO + H(z) (Orange and yellow contours) and SNe + CMB + BAO + H(z) (black and cyan contours). The central regions and the vicinity regions represent $1 \sigma$ contours and $2 \sigma$ contours, respectively.
• Figure 2: The black and grey regions are $1 \sigma$ contours and $2 \sigma$ contours, respectively. The left panel is $w_0$ vs $w_1$ without coupling, and the right panel is $w_0$ vs $w_1$ with coupling in our model.
• Figure 3: The black and grey regions are $1 \sigma$ contours and $2 \sigma$ contours, respectively. The left panel is $\delta$ vs $w_0$, and the right panel is $\Omega_{DM}$ vs $w_1$.
• Figure 4: The black and grey regions are $1 \sigma$ contours and $2 \sigma$ contours, respectively. The left panel is $\delta$ vs $w_1$, and the right panel is $\Omega_{DM}$ vs $w_0$.
• Figure 5: The evolution of $\rho_{DM}/\rho_{DE}$ as a function of scale factor $a(z)$. The dashed line is the interacting model with best-fitted parameters, and the gray region is the 1$\sigma$ uncertainties. The black region represents the $\Lambda$CDM with uncertainties.