Cosmological constraints on extended Galileon models

Antonio De Felice, Shinji Tsujikawa

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

The extended Galileon models possess tracker solutions with de Sitter attractors along which the dark energy equation of state is constant during the matter-dominated epoch, i.e. w DE = -1-s, where s is a positive constant. Even with this phantom equation of state there are viable parameter spaces in which the ghosts and Laplacian instabilities are absent. Using the observational data of the supernovae type Ia, the cosmic microwave background (CMB), and baryon acoustic oscillations, we place constraints on the tracker solutions at the background level and find that the parameter s is constrained to be s = 0.034 -0.034 +0.327 (95 % CL) in the flat Universe. In order to break the degeneracy between the models we also study the evolution of cosmological density perturbations relevant to the large-scale structure (LSS) and the Integrated-Sachs-Wolfe (ISW) effect in CMB. We show that, depending on the model parameters, the LSS and the ISW effect is either positively or negatively correlated. It is then possible to constrain viable parameter spaces further from the observational data of the ISW-LSS cross-correlation as well as from the matter power spectrum.

Original languageEnglish
Article number025
JournalJournal of Cosmology and Astroparticle Physics
Volume2012
Issue number3
DOIs
Publication statusPublished - 2012 Mar
Externally publishedYes

Keywords

  • cosmological perturbation theory
  • dark energy theory
  • modified gravity

ASJC Scopus subject areas

  • Astronomy and Astrophysics

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