Thermodynamics and dark energy

¹ Universidade Federal do Rio Grande do Norte, Departamento de Física, Natal – RN, 59072-970, Brasil
e-mail: raimundosilva@dfte.ufrn.br; heydson@dfte.ufrn.br;
² Universidade do Estado do Rio Grande do Norte, Departamento de Física, Mossoró – RN, 59610-210, Brasil
³ Observatório Nacional, Rua General José Cristino 77, 20921-400 Rio de Janeiro – RJ, Brasil
e-mail: rsousa@on.br; alcaniz@on.br

Received: 14 July 2011
Accepted: 15 September 2011

Abstract

Significant observational effort has been directed to unveiling the nature of the so-called dark energy. However, given the large number of theoretical possibilities, it is possible that this a task cannot be based only on observational data. We discuss some thermodynamic properties of this energy component assuming a general time-dependent equation-of-state parameter w(z) = w₀ + w_af(z), where w₀ and w_a are constants and f(z) may assume different forms. We show that very restrictive bounds can be placed on the w₀ – w_a space when current observational data are combined with the thermodynamic constraints derived.