Cosmological density perturbations in modified gravity theories

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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.
© 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
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1. S. Perlmutter et a/.[Supemova Cosmology Project Collaboration], Astrophys. J. 517, 565, (1999). 2. E. J. Copeland, M. Sami and S. Tsujikawa, Int. J. Mod. Phys. D, 15, 1753 (2006). 3. L. Pogosian and A. Silvestri, Phys. Rev. D 77 023503, (2008). 4. D. J. Eisenstein et al. Astrophys. J. 633: 560-574, (2005). 5. D. N. Spergel et al. [WMAP Collaboration], Astrophys. J. Suppl. 170 377, (2007). 6. E. Linder Phys.Rev D 72 : 043529, (2005). 7. A. de la Cruz-Dombriz, A. Dobado and A. L. Maroto, Phys. Rev D 77 123515 (2008). 8. S. M. Carroll et al.. New J. Phys. 8 323, (2006) ; P Zhang, Phys. Rev. D 73 123504, (2006). 9. S. Tsujikawa, Phys. Rev. D 76 023514, (2007). 10. L. Amendola, R. Gannouji, D. Polarski and S. Tsujikawa, Phys. Rev D 75 083504 (2007).