Cosmological perfect fluids in higher-order gravity

Abstract

We prove that in Robertson-Walker space-times (and in generalized Robertson-Walker spacetimes of dimension greater than 3 with divergence-free Weyl tensor) all higher-order gravitational corrections of the Hilbert-Einstein Lagrangian density $F(R,\square R,...,{\square }^{k}R)$ have the form of perfect fluids in the field equations. This statement definitively allows to deal with dark energy fluids as curvature effects.

arXiv comment6 pages

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• FLRW-Cosmology in Generic Gravity Theories
• Characterizations of a spacetime of quasi-constant sectional curvature and $\mathcal{F}(\mathcal{R})$-gravity
• Geometric Perfect Fluids from Extended Gravity
• Characterizations of Perfect fluid spacetimes obeying $f(\mathcal{R})$-gravity equipped with different gradient solitons
• Linearized Field Equations and Extra Force in $f(R,{\mathbf{T}}^{(n)})$ Extended Gravity
• Gödel-type universes in energy-momentum-squared gravity
• On Nash theory of gravity with matter contents