https://doi.org/10.1140/epjc/s10052-011-1843-7
Regular Article - Theoretical Physics
Oscillations of the F(R) dark energy in the accelerating universe
1
ICE/CSIC and IEEC Campus UAB, Facultat de Ciències, Consejo Superior de Investigaciones Científicas, Torre C5-Parell-2a pl, 08193, Bellaterra (Barcelona), Spain
2
Institució Catalana de Recerca i Estudis Avançats (ICREA), Trento, Italy
3
Tomsk State Pedagogical University, Tomsk, Russia
4
Dipartimento di Fisica, Università di Trento, Trento, Italy
5
Gruppo Collegato di Trento, Istituto Nazionale di Fisica Nucleare, Trento, Italy
* e-mail: elizalde@math.mit.edu
** e-mail: elizalde@ieec.uab.es
Received:
23
November
2011
Published online:
3
February
2012
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.
© Springer-Verlag / Società Italiana di Fisica, 2012