منابع مشابه
The dark energy equation of state
We perform a study of cosmic evolution with an equation of state parameter ω(t) = ω0 + ω1(tḢ/H) by selecting a phenomenological Λ model of the form, Λ̇ ∼ H. This simple proposition explains both linearly expanding and inflationary Universes with a single set of equations. We notice that the inflation leads to a scaling in the equation of state parameter, ω(t), and hence in equation of state. In ...
متن کاملMapping the Dark Energy Equation of State
The acceleration of the expansion of the universe has deep implications for structure formation, the composition of the universe, and its fate. Roughly 70% of the energy density is in a dark energy, whose nature remains unknown. Mapping the expansion history through supernovae, mapping the geometry of the universe and formation of structure through redshift surveys, and mapping the distance to ...
متن کاملDark energy with polytropic equation of state
Equation of state parameter plays a significant role for guessing the real nature of dark energy. In the present paper polytropic equation of state p = ωρn is chosen for some of the kinematical Λ-models viz., Λ ∼ (ȧ/a), Λ ∼ ä/a and Λ ∼ ρ. Although in dust cases (ω = 0) closed form solutions show no dependency on the polytropic index n, but in non-dust situations some new possibilities are opene...
متن کاملThe value of the equation of state of dark energy
From recent CMB and Large Scale Structure observations the value of the equation of state of dark energy, assuming it to be constant in time, is constrained to be −1.3 < w < −0.7 at the 95% confidence level: consistent with dark energy being a classical vacuum term. Here we describe two novel and independent methods, sensitive to different systematics, that give the same value for w and similar...
متن کاملEntropy Growth and the Dark Energy Equation of State ∗
We revisit the conjecture of a generalized second law of thermodynamics which states that the combined entropy of matter and horizons must grow. In an expanding universe a generalized second law restricts the equation of state. In particular, it conflicts with long phases of a phantom, w < −1, equation of state.
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society: Letters
سال: 2008
ISSN: 1745-3925,1745-3933
DOI: 10.1111/j.1745-3933.2008.00468.x