Dark Energy from Wet Dark Fluid

Abstract

We propose a new equation of state for the Dark Energy component of the Universe. It is modeled on the equation of state $p=w(ρ-ρ_{*})$ which can describe a liquid, for example water. We show that its energy density naturally decomposes into a component that behaves as a cosmological constant and one whose energy density scales as $a^{-3(1+w)}$, and fit the parameters specifying the equation of state to the new SNIa data, as well as WMAP and 2dF data. We find that reasonable values of the parameters can be found that give our model the same $χ^2$ as that of $Λ$CDM. A remarkable feature of the model is that we can do all this with $w>0$.

11 pages JHEP 6 figures; v2 added references, candidate microphysical model and edited to conserve length; v3 major revision: images enlarged, paper extended to include new discussion and reformatted