Oscillations of the F(R) dark energy in the accelerating universe

• Published in: The European physical journal. C, Particles and fields Vol. 72; no. 2; pp. 1 - 14
• Main Authors: Elizalde, E., Odintsov, S. D., Sebastiani, L., Zerbini, S.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-02-2012; Springer; Springer Nature B.V
• Subjects: Analysis; Astronomy; Astrophysics and Cosmology; Critical point; Dark energy; Doppler effect; Elementary Particles; Equations of motion; Force and energy; Hadrons; Heavy Ions; Measurement Science and Instrumentation; Nuclear Energy; Nuclear Physics; Numerical analysis; Oscillations; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Red shift; Regular Article - Theoretical Physics; Singularities; String Theory; Time dependence; Toy industry; Dark Energy; Ricci Scalar; Future Singularity; Phantom Divide; Dark Energy Density
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-011-1843-7

Oscillations of the
F
(
R
) dark energy around the phantom divide line,
ω
DE
=−1, both during the matter era and also in the de Sitter epoch are investigated. The analysis during the de Sitter epoch is revisited by expanding the modified equations of motion around the de Sitter solution. Then, during the matter epoch, the time dependence of the dark energy perturbations is discussed by using two different local expansions. For high values of the red shift, the matter epoch is a stable point of the theory, giving the possibility to expand the
F
(
R
)-functions in terms of the dark energy perturbations. In the late-time matter era, the realistic case is considered where dark energy tends to a constant. The results obtained are confirmed by precise numerical computation on a specific model of exponential gravity. A novel and very detailed discussion is provided on the critical points in the matter era and on the relation of the oscillations with possible singularities.