Thermodynamics of Dark Energy

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.

12 pages, presented at BW2007 workshop, Djerdap, Serbia, 2-9 Sep 2007, typos corrected