Quasar-Lyman $\hat{I}\pm$ Forest Cross-Correlation from BOSS DR11 : Baryon Acoustic Oscillations

Abstract

We measure the large-scale cross-correlation of quasars with the Lyman alpha forest absorption, using over 164,000 quasars from Data Release 11 of the SDSS-III Baryon Oscillation Spectroscopic Survey. We extend the previous study of roughly 60,000 quasars from Data Release 9 to larger separations, allowing a measurement of the Baryonic Acoustic Oscillation (BAO) scale along the line of sight $c/(H(z=2.36)r_s)=9.0\pm 0.3$ and across the line of sight $D_A(z=2.36)/r_s=10.8\pm 0.4$, consistent with CMB and other BAO data. Using the best fit value of the sound horizon from Planck data ($r_s=147.49Mpc$), we can translate these results to a measurement of the Hubble parameter of $H(z=2.36)=226\pm 8km/s/Mpc$ and of the angular diameter distance of $D_A(z=2.36)=1590\pm 60Mpc$. The measured cross-correlation function and an update of the code to fit the BAO scale (baofit) are made publicly available.

26 pages, 7 figures, version published by JCAP, with some extra comments suggested by the referee. Results unchanged from previous version