Gradient expansion(s) and dark energy

Abstract

Motivated by recent claims stating that the acceleration of the present Universe is due to fluctuations with wavelength larger than the Hubble radius, we present a general analysis of various perturbative solutions of fully inhomogeneous Einstein equations supplemented by a perfect fluid. The equivalence of formally different gradient expansions is demonstrated. If the barotropic index vanishes, the deceleration parameter is always positive semi-definite.

17 pages, no figures

References in corpus (7)

• Properties of singularities in (phantom) dark energy universe
• More General Sudden Singularities
• New Isotropic and Anisotropic Sudden Singularities
• Vector Perturbations in a Contracting Universe
• Vector fluctuations from multidimensional curvature bounces
• Perturbations in a Holographic Universe and in Other Stiff Fluid Cosmologies
• Rotational inhomogeneities from pre-big bang?

Cited by in corpus (13)

• Dynamics of dark energy
• Dark Energy and Dark Gravity
• The acceleration of the universe and the physics behind it
• Large non-Gaussianity in multiple-field inflation
• Observational constraints on phantom-like braneworld cosmologies
• Asymmetric inflation: exact solutions
• Can a dust dominated universe have accelerated expansion?
• Dark energy, integrated Sachs-Wolfe effect and large-scale magnetic fields
• Gradient expansion, curvature perturbations and magnetized plasmas
• Uniform gradient expansions
• Long-Wavelength Modes of Cosmological Scalar Fields
• Cosmic Acceleration Driven by Mirage Inhomogeneities
• Quasiadiabatic modes from viscous inhomogeneities