Dark energy and dark matter from an additional adiabatic fluid

作者：Dun**y Peter K S^*; Luongo Orlando^*; Reverberi Lorenzo^*

来源：PHYSICAL REVIEW D, 2016, 94(8): 083525.

DOI：10.1103/PhysRevD.94.083525

The dark sector is described by an additional barotropic fluid which evolves adiabatically during the Universe's history and whose adiabatic exponent gamma is derived from the standard definitions of specific heats. Although in general gamma is a function of the redshift, the Hubble parameter and its derivatives, we find that our assumptions lead necessarily to solutions with gamma = constant in a Friedmann-Lemaitre-Robertson-Walker universe. The adiabatic fluid acts effectively as the sum of two distinct components, one evolving like nonrelativistic matter and the other depending on the value of the adiabatic index. This makes the model particularly interesting as a way of simultaneously explaining the nature of both dark energy and dark matter, at least at the level of the background cosmology. The Lambda CDM model is included in this family of theories when. gamma = 0. We fit our model to supernovae Ia, H(z) and baryonic acoustic oscillation data, discussing the model selection criteria. The implications for the early Universe and the growth of small perturbations in this model are also discussed.

• 出版日期2016-10-26