Matter instabilities in general Gauss-Bonnet gravity

Antonio De Felice, David F. Mota, and Shinji Tsujikawa
Phys. Rev. D 81, 023532 – Published 29 January 2010

Abstract

We study the evolution of cosmological perturbations in f(G) gravity, where the Lagrangian is the sum of a Ricci scalar R and an arbitrary function f in terms of a Gauss-Bonnet term G. We derive the equations for perturbations assuming matter to be described by a perfect fluid with a constant equation of state w. We show that density perturbations in perfect fluids exhibit negative instabilities during both the radiation and the matter domination, irrespective of the form of f(G). This growth of perturbations gets stronger on smaller scales, which is difficult to be compatible with the observed galaxy spectrum unless the deviation from general relativity is very small. Thus f(G) cosmological models are effectively ruled out from this ultraviolet instability, even though they can be compatible with the late-time cosmic acceleration and local gravity constraints.

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  • Received 9 November 2009

DOI:https://doi.org/10.1103/PhysRevD.81.023532

©2010 American Physical Society

Authors & Affiliations

Antonio De Felice1, David F. Mota2, and Shinji Tsujikawa1

  • 1Department of Physics, Faculty of Science, Tokyo University of Science, 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
  • 2Institute of Theoretical Astrophysics, University of Oslo, 0315, Oslo, Norway

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Vol. 81, Iss. 2 — 15 January 2010

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