| Full text | |
| Author(s): |
Total Authors: 2
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| Affiliation: | [1] Univ Sao Paulo, Dept Astron, BR-05508900 Sao Paulo - Brazil
Total Affiliations: 1
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| Document type: | Journal article |
| Source: | Physical Review D; v. 78, n. 8, p. 083504, 2008. |
| Web of Science Citations: | 30 |
| Abstract | |
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) | |
| FAPESP's process: | 04/13668-0 - Cosmology in the era of precision: dark energy, dark matter and background cosmic radiation |
| Grantee: | Jose Ademir Sales de Lima |
| Support Opportunities: | Research Projects - Thematic Grants |