Stable, Accelerating Universes in Modified Gravity

Abstract

Modifications to gravity that add additional functions of the Ricci curvature to the Einstein-Hilbert action -- collectively known as $f(R)$ theories -- have been studied in great detail. When considered as complete theories of gravity they can generate non-perturbative deviations from the general relativistic predictions in the solar system, and the simplest models show instabilites on cosmological scales. Here we show that it is possible to treat $f(R)=R\pm {\mu }^4/R$ gravity in a perturbative fashion such that it shows no instabilities on cosmological scales and, in the solar system, is consistent with measurements of the PPN parameters. We show that such a theory produces a spatially flat, accelerating universe, even in the absence of dark energy and when the matter density is too small to close the universe in the general relativistic case.

5 pages, 1 figure, matches published version

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Cited by in corpus (16)

• f(R) Theories Of Gravity
• Unified cosmic history in modified gravity: from F(R) theory to Lorentz non-invariant models
• Probes and Tests of Strong-Field Gravity with Observations in the Electromagnetic Spectrum
• Constraints on Perturbative f(R) Gravity via Neutron Stars
• Neutron Stars in f(R) Gravity with Perturbative Constraints
• Gödel-type universes in f(R) gravity
• Constraining Parity Violation in Gravity with Measurements of Neutron-Star Moments of Inertia
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• On perturbative constraints for vacuum f(R) gravity
• Dipole magnetic field of neutron stars in $f(R)$ gravity
• Origin Gaps and the Eternal Sunshine of the Second-Order Pendulum