Measurements of D_A and H at z=2.4 from the SDSS-III/DR11 BOSS Lyman-alpha sample

We present the most precise measures of the Baryon Acoustic Oscillation (BAO) scale at z=2.4 from the 3-dimensional clustering of the Lyman alpha forest. The Hubble parameter (BAO scale along the line of sight) is measured to 3% precision. The angular diameter distance (perpendicular to the line of sight) is measured to 5% precision. These results make use of the Sloan Digital Sky Survey III (SDSS-III) Data Release 11 (DR11), with 135 000 high-redshift quasar spectra covering 9000 square degrees. This study supersedes the previous measurements of Busca et al. (2013) and Slosar et al. (2013) with a gain of nearly a factor of three in the amount of Lyman alpha spectra data. We also perform a detailed study of the covariance matrix of the Lyman alpha correlation, which is validated with both simulations and subsampling (data-only) techniques.