Constraints on f(R) theory and Galileons from the latest data of galaxy redshift surveys

TL;DR

This paper uses galaxy redshift survey data to constrain modified gravity models like f(R) and Galileons, finding that only certain parameter ranges are consistent with observations, thus narrowing viable theories for dark energy.

Contribution

It provides the first comprehensive constraints on f(R) and Galileon models using recent RSD data, highlighting the viability of extended Galileon scenarios.

Findings

f(R) model parameters close to Lambda-CDM are favored

Covariant Galileon model is strongly disfavored by RSD data

Extended Galileon models can be consistent with observations within 2 sigma

Abstract

The growth rate of matter density perturbations has been measured from redshift-space distortion (RSD) in the galaxy power spectrum. We constrain the model parameter space for representative modified gravity models to explain the dark energy problem, by using the recent data of f_m(z)sigma_8(z) at the redshifts z = 0.06--0.8 measured by WiggleZ, SDSS LRG, BOSS, and 6dFGRS. We first test the Hu-Sawicki's f(R) dark energy model, and find that only the parameter region close to the standard Lambda Cold Dark Matter (Lambda-CDM) model is allowed (lambda > 12 and 5 for n = 1.5 and 2, respectively, at 95% CL). We then investigate the covariant Galileon model and show that the parameter space consistent with the background expansion history is excluded by the RSD data at more than 10 sigma because of the too large growth rate predicted by the theory. Finally, we consider the extended Galileon scenario, and we find that, in contrast to the covariant Galileon, there is a model parameter space for a tracker solution that is consistent with the RSD data within a 2 sigma level.