The Lyman-alpha forest in three dimensions: measurements of large scale
  flux correlations from BOSS 1st-year data
  Using a sample of approximately 14,000 z>2.1 quasars observed in the first
year of the Baryon Oscillation Spectroscopic Survey (BOSS), we measure the
three-dimensional correlation function of absorption in the Lyman-alpha forest.
The angle-averaged correlation function of transmitted flux (F = exp(-tau)) is
securely detected out to comoving separations of 60 Mpc/h, the first detection
of flux correlations across widely separated sightlines. A quadrupole
distortion of the redshift-space correlation function by peculiar velocities,
the signature of the gravitational instability origin of structure in the
Lyman-alpha forest, is also detected at high significance. We obtain a good fit
to the data assuming linear theory redshift-space distortion and linear bias of
the transmitted flux, relative to the matter fluctuations of a standard LCDM
cosmological model (inflationary cold dark matter with a cosmological
constant). At 95% confidence, we find a linear bias parameter 0.16<b<0.24 and
redshift-distortion parameter 0.44<beta<1.20, at central redshift z=2.25, with
a well constrained combination b(1+\beta)=0.336 +/- 0.012. The errors on beta
are asymmetric, with beta=0 excluded at over 5 sigma confidence level. The
value of beta is somewhat low compared to theoretical predictions, and our
tests on synthetic data suggest that it is depressed (relative to expectations
for the Lyman-alpha forest alone) by the presence of high column density
systems and metal line absorption. These results set the stage for cosmological
parameter determinations from three-dimensional structure in the Lyman-alpha
forest, including anticipated constraints on dark energy from baryon acoustic
oscillations.
