Growth rate of cosmological perturbations at z ~ 0.1 from a new observational test

TL;DR

This paper introduces a new observational test using galaxy luminosity variations and peculiar velocities to measure the growth rate of cosmological perturbations at z ~ 0.1, supporting the ΛCDM model.

Contribution

It presents a novel method combining galaxy luminosity and velocity data to estimate the growth rate of structures in the universe.

Findings

Estimated growth rate fσ8 = 0.37 ± 0.13 at z ~ 0.1

Results agree with ΛCDM predictions

Method is competitive with traditional techniques

Abstract

Spatial variations in the distribution of galaxy luminosities, estimated from redshifts as distance proxies, are correlated with the peculiar velocity field. Comparing these variations with the peculiar velocities inferred from galaxy redshift surveys is a powerful test of gravity and dark energy theories on cosmological scales. Using ~ 2 $\times$ 10$^{5}$ galaxies from the SDSS Data Release 7, we perform this test in the framework of gravitational instability to estimate the normalized growth rate of density perturbations f$\sigma_{8}$ = 0.37 +/- 0.13 at z ~ 0.1, which is in agreement with the $\Lambda$CDM scenario. This unique measurement is complementary to those obtained with more traditional methods, including clustering analysis. The estimated accuracy at z ~ 0.1 is competitive with other methods when applied to similar datasets.