Scalar Field as Dark Energy Accelerating Expansion of the Universe

TL;DR

This paper analyzes scalar and tachyon fields as models for dark energy driving the universe's accelerated expansion, reconstructing their potentials and field evolution based on observational data.

Contribution

It introduces a method to reconstruct scalar and tachyon field potentials from cosmological observations for dark energy models.

Findings

Reconstructed potentials V(φ) for scalar and tachyon fields.

Demonstrated the rolling down of potentials to minima.

Analyzed models with constant equation-of-state parameter w_{de} < -1/3.

Abstract

The features of a homogeneous scalar field $\phi$ with classical Lagrangian $L=\phi_{;i}\phi^{;i}/2-V(\phi)$ and tachyon field Lagrangian $L=-V(\phi)\sqrt{1-\phi_{;i}\phi^{;i}}$ causing the observable accelerated expansion of the Universe are analyzed. The models with constant equation-of-state parameter $w_{de}=p_{de}/\rho_{de}<-1/3$ are studied. For both cases the fields $\phi(a)$ and potentials $V(a)$ are reconstucted for the parameters of cosmological model of the Universe derived from the observations. The effect of rolling down of the potential $V(\phi)$ to minimum is shown.