On the self-interaction of dark energy in a ghost-condensate model

TL;DR

This paper investigates the constraints on scalar field self-interaction in a ghost-condensate dark energy model, revealing that zero self-interaction is too restrictive and deriving conditions for viable potentials consistent with cosmic evolution.

Contribution

It derives a quadratic restriction on the scalar potential in ghost-condensate models and shows how this encompasses phantom cosmology in certain limits.

Findings

Zero self-interaction is too restrictive for universe evolution.

The quadratic restriction admits real solutions for the scalar potential.

The model reproduces phantom cosmology potential in a specific limit.

Abstract

In a ghost-condensate model of dark energy the combined dynamics of the scalar field and gravitation is shown to impose non-trivial restriction on the self-interaction of the scalar field. Using this restriction we show that the choice of a zero self-interaction leads to a situation too restrictive for the general evolution of the universe. This restriction, obtained in the form of a quadratic equation of the scalar potential, is demonstrated to admit real solutions. Also, in the appropriate limit it reproduces the potential in the phantom cosmology.