Chemical potential and the nature of dark energy: The case of a phantom field

Autor(es)

Lima, J. A. S. ^[1] ; Pereira, S. H. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Astron, BR-05508900 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Physical Review D; v. 78, n. 8, p. 083504, 2008.
• Citações Web of Science: 30

Resumo

The influence of a possible nonzero chemical potential mu on the nature of dark energy is investigated by assuming that the dark energy is a relativistic perfect simple fluid obeying the equation of state, p=omega rho (omega < 0, constant). The entropy condition, S >= 0, implies that the possible values of omega are heavily dependent on the magnitude, as well as on the sign of the chemical potential. For mu > 0, the omega parameter must be greater than -1 (vacuum is forbidden) while for mu < 0 not only the vacuum but even a phantomlike behavior (omega <-1) is allowed. In any case, the ratio between the chemical potential and temperature remains constant, that is, mu/T=mu(0)/T-0. Assuming that the dark energy constituents have either a bosonic or fermionic nature, the general form of the spectrum is also proposed. For bosons mu is always negative and the extended Wien's law allows only a dark component with omega <-1/2, which includes vacuum and the phantomlike cases. The same happens in the fermionic branch for mu < 0. However, fermionic particles with mu > 0 are permitted only if -1 <omega <-1/2. The thermodynamics and statistical arguments constrain the equation-of-state parameter to be omega <-1/2, a result surprisingly close to the maximal value required to accelerate a Friedmann-Robertson-Walker-type universe dominated by matter and dark energy (omega less than or similar to-10/21). (AU)

• Processo FAPESP: 04/13668-0 - Cosmologia na era da precisão: energia escura, matéria escura e radiação cósmica de fundo
• Beneficiário: Jose Ademir Sales de Lima
• Modalidade de apoio: Auxílio à Pesquisa - Temático