Thermodynamics of Dark Energy

TL;DR

This paper explores the thermodynamic properties of dark energy modeled as a self-interacting complex scalar, revealing that certain models can have positive entropy even in the phantom regime.

Contribution

It demonstrates the equivalence between self-interacting complex scalar fields and kinetic k-essence models, and analyzes their thermodynamic behavior.

Findings

Dark energy modeled as a complex scalar can have positive entropy in the phantom regime.

Self-interacting scalar fields are equivalent to kinetic k-essence models under certain conditions.

Dark-energy thermodynamics can be consistent with positive entropy even when in the phantom regime.

Abstract

Thermodynamic properties of dark energy are discussed assuming that dark energy is described in terms of a selfinteracting complex scalar. We first show that, under certain assumptions, selfinteracting complex scalar field theories are equivalent to purely kinetic k-essence models. Then we analyze the themal properties of k-essence and in particular we show that dark-energy in the phantom regime does not necessarily yield negative entropy.