We apply the reconstruction technique to the clustering of galaxies from the Sloan Digital Sky Survey Data Release 7 ( SDSS DR7 ) Luminous Red Galaxy sample , sharpening the baryon acoustic oscillation ( BAO ) feature and achieving a 1.9 % measurement of the distance to z = 0.35 .
This is the first application of reconstruction of the BAO feature in a galaxy redshift survey .
We update the reconstruction algorithm of ( ) to account for the effects of survey geometry as well as redshift-space distortions and validate it on 160 LasDamas simulations .
We demonstrate that reconstruction sharpens the BAO feature in the angle averaged galaxy correlation function , reducing the nonlinear smoothing scale \Sigma _ { nl } from 8.1 Mpc/ h to 4.4 Mpc/ h .
Reconstruction also significantly reduces the effects of redshift-space distortions at the BAO scale , isotropizing the correlation function .
This sharpened BAO feature yields an unbiased distance estimate ( < 0.2 \% ) and reduces the scatter from 3.3 \% to 2.1 \% .
We demonstrate the robustness of these results to the various reconstruction parameters , including the smoothing scale , the galaxy bias and the linear growth rate .
Applying this reconstruction algorithm to the Sloan Digital Sky Survey ( SDSS ) Luminous Red Galaxy ( LRG ) Data Release 7 ( DR7 ) sample improves the significance of the BAO feature in these data from 3.3 \sigma for the unreconstructed correlation function , to 4.2 \sigma after reconstruction .
We estimate a relative distance scale D _ { V } / r _ { s } to z = 0.35 of 8.88 ~ { } \pm~ { } 0.17 , where r _ { s } is the sound horizon and D _ { V } \equiv ( D _ { A } ^ { 2 } H ^ { -1 } ) ^ { 1 / 3 } is a combination of the angular diameter distance D _ { A } and Hubble parameter H .
Assuming a sound horizon of 154.25 Mpc , this translates into a distance measurement D _ { V } ( z = 0.35 ) = 1.356 ~ { } \pm~ { } 0.025 { Gpc } .
We find that reconstruction reduces the distance error in the DR7 sample from 3.5 % to 1.9 % , equivalent to a survey with three times the volume of SDSS .