Scalar Field as Dark Energy Accelerating Expansion of the Universe

Abstract

The features of a homogeneous scalar field $\varphi$ with classical Lagrangian $L={\varphi }_{;i}{\varphi }^{;i}/2-V(\varphi )$ and tachyon field Lagrangian $L=-V(\varphi )\sqrt{1-{\varphi }_{;i}{\varphi }^{;i}}$ 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 $\varphi (a)$ 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 $V(\varphi )$ to minimum is shown.

arXiv comment14 pages, 14 figures, accepted for publication by Kinematics and Physics of Celestial Bodies (UA)

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• Perturbed dark energy: classical scalar field versus tachyon
• An analysis of Born-Infeld boson compact objects