Conditions for the cosmological viability of the most general scalar-tensor theories and their applications to extended Galileon dark energy models

Antonio De Felice, Shinji Tsujikawa

Research output: Contribution to journalArticle

124 Citations (Scopus)

Abstract

In the Horndeski's most general scalar-tensor theories with second-order field equations, we derive the conditions for the avoidance of ghosts and Laplacian instabilities associated with scalar, tensor, and vector perturbations in the presence of two perfect fluids on the flat Friedmann-Lematre-Robertson- Walker (FLRW) background. Our general results are useful for the construction of theoretically consistent models of dark energy. We apply our formulas to extended Galileon models in which a tracker solution with an equation of state smaller than -1 is present. We clarify the allowed parameter space in which the ghosts and Laplacian instabilities are absent and we numerically confirm that such models are indeed cosmologically viable.

Original languageEnglish
Article number007
JournalJournal of Cosmology and Astroparticle Physics
Volume2012
Issue number2
DOIs
Publication statusPublished - 2012 Feb
Externally publishedYes

Keywords

  • cosmological perturbation theory
  • dark energy theory
  • gravity
  • modified gravity

ASJC Scopus subject areas

  • Astronomy and Astrophysics

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