Scalar perturbations in cosmological f (R) models: the cosmic screening approach

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Akarsu Ö., BRİLENKOV R., Eingorn M., SHULGA V., Zhuk A.

EUROPEAN PHYSICAL JOURNAL C, vol.78, no.8, 2018 (SCI-Expanded)

• Publication Type: Article / Article
• Volume: 78 Issue: 8
• Publication Date: 2018
• Doi Number: 10.1140/epjc/s10052-018-6091-7
• Journal Name: EUROPEAN PHYSICAL JOURNAL C
• Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
• Istanbul Technical University Affiliated: Yes

Abstract

We investigate cosmological perturbations for nonlinear f (R) models within the cosmic screening approach. Matter is considered both in the form of a set of discrete point-like massive bodies and in the form of a continuous pressure-less perfect fluid. We perform full relativistic analysis of the first-order theory of scalar perturbations for arbitrary nonlinear f (R) models and demonstrate that scalar potentials Phi (t, r) and psi (t, r) are determined by a system of only two master equations. Our equations are applicable at all spatial scales as long as the approximation delta R/(R) over bar << 1 (which is usually assumed in studies devoted to cosmological perturbations in f (R) models) works.