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arXiv · 0901.1213

Unified dark energy thermodynamics: varying w and the -1-crossing

Emmanuel N. Saridakis·Pedro F. Gonzalez-Diaz·Carmen L. Siguenza
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Abstract

We investigate, in a unified and general way, the thermodynamic properties of dark energy with an arbitrary, varying equation-of-state parameter w(a). We find that all quantities are well defined and regular for every w(a), including at the -1-crossing, with the temperature being negative in the phantom regime (w(a)<-1) and positive in the quintessence one (w(a)>-1). The density and entropy are always positive while the chemical potential can be arbitrary. At the -1-crossing, both temperature and chemical potential are zero. The temperature negativity can only be interpreted in the quantum framework. The regular behavior of all quantities at the -1-crossing, leads to the conclusion that such a crossing does not correspond to a phase transition, but rather to a smooth cross-over.

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Emmanuel N. Saridakis, Pedro F. Gonzalez-Diaz, Carmen L. Siguenza. 2009-08-03. Unified dark energy thermodynamics: varying w and the -1-crossing. https://doi.org/10.1088/0264-9381%2F26%2F16%2F165003

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