Testing general relativity with the multipole spectra of the SDSS luminous red galaxies

TL;DR

This study tests general relativity on large cosmic scales by measuring the growth rate of density perturbations using SDSS luminous red galaxies, finding results consistent with Einstein's theory within current uncertainties.

Contribution

It provides a new measurement of the growth index b3 using SDSS data, supporting general relativity over alternative models like DGP.

Findings

Measured b3=0.62(c4_8-0.8) b1 0.11, consistent with GR

High c4_8 (c4_8  0.87) favors DGP model

Results support Einstein's gravity on cosmological scales

Abstract

As a test of general relativity on cosmological scales, we measure the \gamma parameter for the growth rate of density perturbations using the redshift-space distortion of the luminous red galaxies in the Sloan Digital Sky Survey (SDSS). Assuming the cosmological constant model, which matches the results of the WMAP experiment, we find \gamma=0.62+1.8(\sigma_8-0.8) \pm 0.11 at 1-sigma confidence level, which is consistent with the prediction of general relativity, \gamma\simeq0.55\sim0.56. Rather high value of \sigma_8(\geq0.87) is required to be consistent with the prediction of the cosmological DGP model, \gamma\simeq0.68.