Can structure formation distinguish ΛCDM from non-minimal f(R) Gravity?

Abstract

Non-minimally coupled f(R) gravity model is an interesting approach to explain the late time acceleration of the Universe without introducing any exotic matter component in the energy budget of the Universe. But distinguishing such model with the concordance ΛCDM model using present observational data is a serious challenge. In this paper, we address this issue using the observations related to the growth of matter over density g(z) as measured by different galaxy surveys. As background cosmology is not sufficient to distinguish different dark energy models, we first find out the functional form for f(R) (which is non-minimally coupled to the matter lagrangian) that produces the similar background cosmology as in ΛCDM. Subsequently we calculate the growth for the matter over density g(z) for such non minimally coupled f(R) models and compare them with the ΛCDM Universe. We also use the measurements of g(z)σ_{8}(z) by different galaxy surveys to reconstruct the behavior for g(z) and σ_{8}(z) for both the non-minimally coupled f(R) gravity models as well as for the ΛCDM. Our results show that there is a small but finite window where one can distinguish the non-minimally coupled f(R) models with the concordance ΛCDM.