Can structure formation distinguish \Lambda CDM from non-minimal f(R) Gravity?

TL;DR

This paper investigates whether structure formation observations can differentiate non-minimally coupled f(R) gravity models from the standard mbda CDM model by analyzing growth of matter density and comparing with galaxy survey data.

Contribution

It derives specific f(R) functions that mimic mbda CDM background evolution and compares their growth predictions with observational data to identify distinguishable features.

Findings

Small but finite window to distinguish models using growth data

Non-minimally coupled f(R) models can mimic mbda CDM background

Growth of matter density provides a potential discriminant

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 \Lambda CDM 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 \Lambda CDM. 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 \Lambda CDM Universe. We also use the measurements of g(z)\sigma_{8}(z) by different galaxy surveys to reconstruct the behavior for g(z) and \sigma_{8}(z) for both the non-minimally coupled f(R) gravity models as well as for the \Lambda CDM. 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 \Lambda CDM.