Cosmological density perturbations in modified gravity theories



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Cruz Dombriz, Álvaro de la and Dobado González, Antonio and López Maroto, Antonio (2009) Cosmological density perturbations in modified gravity theories. In Physics and mathematics of gravitation. Amer Inst Physics, pp. 252-255. ISBN 978-0-7354-0658-2

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In the context of f(R) theories of gravity, we study the cosmological evolution of scalar perturbations by using a completely general procedure. We find that the exact fourth-order differential equation for the matter density perturbations in the longitudinal gauge, reduces to a second-order equation for sub-Hubble modes. This simplification 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 f(R) adequately describing the present phase of accelerated expansion and satisfying local gravity tests, it does give a correct description for the evolution of perturbations.

Item Type:Book Section
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© American Institute of Physics. Spanish Relativity Conference (31. 2008. Salamanca, España).
We would like to thank J. A. R. Cembranos and J. Beltran. This work has been supported by the DGICYT (Spain) under projects FPA 2004-02602 and 2005-02327, CAM/UCM 910309 and by UCM-SantanderPR34/07-15875

Uncontrolled Keywords:Cosmology, Modified Theories of Gravity
Subjects:Sciences > Physics
ID Code:21422
Deposited On:11 Jun 2013 14:46
Last Modified:31 Dec 2020 00:01

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