A Field Theory Model for Dark Matter and Dark Energy in Interaction

Abstract

We propose a field theory model for dark energy and dark matter in interaction. Comparing the classical solutions of the field equations with the observations of the CMB shift parameter, BAO, lookback time and Gold supernovae sample, we observe a possible interaction between dark sectors with energy decay from dark energy into dark matter. The observed interaction provides an alleviation to the coincidence problem.

Figures (10)

• Figure 1: Results corresponding to the global best fit (lookback time + CMB + BAO + SNe Ia).a) Theoretical distance modulus compared to 182 SNe Ia data. b) Theoretical $t_L(z)$ versus 67 galaxy clusters data.
• Figure 2: Relative densities of Dark Energy and Dark Matter, $\Omega_{\phi}$ and $\Omega_{\Psi}$, as functions of the scale factor $a$. a) for $\phi_0$ constant ($\phi_0H_0 = 2.5$). The dot-dot-dashed, dot-dashed, solid, dashed and dotted lines are for $\frac{\beta}{M\sqrt{\alpha}H_0} = +0.125$, $\frac{\beta}{M\sqrt{\alpha}H_0} = +0.0625$, $\frac{\beta}{M\sqrt{\alpha}H_0} = 0$, $\frac{\beta}{M\sqrt{\alpha}H_0} = -0.125$ and $\frac{\beta}{M\sqrt{\alpha}H_0} = -0.25$, respectively. b) for $\frac{\beta}{M\sqrt{\alpha}}$ constant ($\frac{\beta}{M\sqrt{\alpha}} = 0$). The dot-dot-dashed, dot-dashed, solid, dashed and dotted lines are for $\phi_0H_0 = 1.8$, $\phi_0H_0 = 2.0$, $\phi_0H_0 = 2.5$, $\phi_0H_0 = 5.0$ and $\phi_0H_0 = 7.5$, respectively.
• Figure 3: Two dimensional distribution of $\beta$ and $\phi_0$ ($1\sigma$ and $2\sigma$ contours). Notice that there is a strong degeneracy. $\beta$ can go to arbitrarily large negative values. For positive values the function decays quickly to zero. The expectation of $\beta$ cannot be computed due to the fact that the distribution does not approach zero. Thus, $\beta$ should most probably be negative.
• Figure 4: The $\beta$ likelihood function shows a behavior confirming the speculations arising in the previous figure. It is most probable that it is negative.
• Figure 5: Two dimensional curves displaying the probability distributions of $\beta$ versus $\Omega_{\Psi_0}$, $\phi_0$ versus $h$ and $\phi_0$ versus $\Omega_{\Psi_0}$, respectively.