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 \sim 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 \pm 0.13 at z \sim 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 \sim 0.1 is competitive with other methods when applied to similar datasets .