Matter perturbations in Galileon cosmology

Antonio De Felice, Ryotaro Kase, Shinji Tsujikawa

Research output: Contribution to journalArticle

106 Citations (Scopus)

Abstract

We study the evolution of matter density perturbations in Galileon cosmology where the late-time cosmic acceleration can be realized by a field kinetic energy. We obtain full perturbation equations at linear order in the presence of five covariant Lagrangians Li (i=1,5) satisfying the Galileon symmetry ∂μφ→∂μφ +bμ in the flat space-time. The equations for a matter perturbation as well as an effective gravitational potential are derived under a quasistatic approximation on subhorizon scales. This approximation can reproduce full numerical solutions with high accuracy for the wavelengths relevant to large-scale structures. For the model parameters constrained by the background expansion history of the Universe, the growth rate of matter perturbations is larger than that in the Λ-cold dark matter model, with the growth index γ today typically smaller than 0.4. We also find that, even on very large scales associated with the integrated-Sachs-Wolfe effect in cosmic microwave background temperature anisotropies, the effective gravitational potential exhibits a temporal growth during the transition from the matter era to the epoch of cosmic acceleration. These properties are useful to distinguish the Galileon model from the Λ-cold dark matter model in future high-precision observations.

Original languageEnglish
Article number043515
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume83
Issue number4
DOIs
Publication statusPublished - 2011 Feb 17
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)

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