%0 Journal Article
%A Abebe, Amare
%A Abdelwahab, Mohamed
%A Cruz Dombriz, Álvaro de la
%A Dunsby, Peter K. S.
%T Covariant gauge-invariant perturbations in multifluid f (R) gravity
%D 2012
%@ 0264-9381
%U https://hdl.handle.net/20.500.14352/44480
%X We study the evolution of scalar cosmological perturbations in the 1 + 3 covariant gauge-invariant formalism for generic f(R) theories of gravity. Extending previous works, we give a complete set of equations describing the evolution of matter and curvature fluctuations for a multi-fluid cosmological medium. We then specialize to a radiation-dust fluid described by barotropic equations of state and solve the perturbation equations around a background solution of R^n gravity. In particular, we study exact solutions for scales much smaller and much larger than the Hubble radius and show that n > 2/3 in order to have a growth rate compatible with the Mészáros effect.
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