Coupled Quintessence and Phantom Based On a Dilaton

TL;DR

This paper explores dilatonic dark energy models with positive and negative kinetic energy, analyzing attractor solutions and their implications for cosmic evolution, including numerical studies of coupling effects.

Contribution

It introduces a detailed analysis of attractor solutions in dilaton-based dark energy models with both quintessence and phantom cases, including mathematical and numerical results.

Findings

Attractor solutions exist regardless of matter coupling.

In Mexican hat potential, attractor behavior and evolution of parameters are characterized.

Coupling term influences the evolution of specific cosmological variables.

Abstract

Based on dilatonic dark energy model, we consider two cases: dilaton field with positive kinetic energy(coupled quintessence) and with negative kinetic energy(phantom). In the two cases, we investigate the existence of attractor solutions which correspond to an equation of state parameter $\omega=-1$ and a cosmic density parameter $\Omega_\sigma=1$. We find that the coupled term between matter and dilaton can't affect the existence of attractor solutions. In the Mexican hat potential, the attractor behaviors, the evolution of state parameter $\omega$ and cosmic density parameter $\Omega$, are shown mathematically. Finally, we show the effect of coupling term on the evolution of $X(\frac{\sigma}{\sigma_0})$ and $Y(\frac{\dot{\sigma}}{\sigma^2_0})$ with respect to $N(lna)$ numerically.