Constraints on scalar-tensor models of dark energy from observational and local gravity tests

Shinji Tsujikawa, Kotub Uddin, Shuntaro Mizuno, Reza Tavakol, Jun'Ichi Yokoyama

Research output: Contribution to journalArticle

108 Citations (Scopus)

Abstract

We construct a family of viable scalar-tensor models of dark energy (DE) which possess a phase of late-time acceleration preceded by a standard matter era, while at the same time satisfying the local gravity constraints (LGC). The coupling Q between the scalar field and the nonrelativistic matter in the Einstein frame is assumed to be constant in our scenario, which is a generalization of f(R) gravity theories corresponding to the coupling Q=-1/6. We find that these models can be made compatible with local gravity constraints even when |Q| is of the order of unity through a chameleon mechanism, if the scalar-field potential is chosen to have a sufficiently large mass in the high-curvature regions. We show that these models generally lead to the divergence of the equation of state of DE, which occurs at smaller redshifts as the deviation from the ΛCDM model becomes more significant. We also study the evolution of matter density perturbations and employ them to place bounds on the coupling |Q| as well as model parameters of the field potential from observations of the matter power spectrum and the cosmic microwave background (CMB) anisotropies. We find that, as long as |Q| is smaller than the order of unity, there exist allowed parameter regions that are consistent with both observational and local gravity constraints.

Original languageEnglish
Article number103009
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume77
Issue number10
DOIs
Publication statusPublished - 2008 May 21
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Nuclear and High Energy Physics
  • Mathematical Physics

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