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On the evolution of density perturbations in f(R) theories of gravity

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arxiv 0802.2999 v2 pith:2R2VUQF2 submitted 2008-02-21 astro-ph

classification astro-ph
keywords perturbationsequationevolutiongravitydensityfunctionsgeneralquasi-static
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abstract

In the context of $f(R)$ theories of gravity, we study the evolution of scalar cosmological perturbations in the metric formalism. Using a completely general procedure, we find the exact fourth-order differential equation for the matter density perturbations in the longitudinal gauge. In the case of sub-Hubble modes, the expression reduces to a second-order equation which is compared with the standard (quasi-static) equation used in the literature. We show that for general $f(R)$ functions the quasi-static approximation is not justified. However, for those functions adequately describing the present phase of accelerated expansion and satisfying local gravity tests, it provides a correct description for the evolution of perturbations.

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Cited by 2 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Differential Obstructions to Curvature-Dependent Conformal Transformations

    gr-qc 2026-08 accept novelty 6.0 of 10

    Curvature-dependent conformal transformations such as g-tilde = F(R[g])g are not local changes of metric variables: their inverse requires solving a differential equation, so no finite-jet metric-only inverse exists g...

  2. Cosmological phase space of generalized hybrid metric-Palatini theories of gravity

    gr-qc 2019-08 conditional novelty 6.0 of 10

    A dynamical-systems analysis of f(R,ℛ) hybrid metric-Palatini gravity shows no global attractors in the cosmological phase space and only two classes of fixed-point scale factors, one of which predicts a jerk paramete...

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