Gravitational Lensing Effects on the Baryonic Acoustic Oscillation
  Signature in the Redshift-Space Correlation Function
  Measurements of the baryonic acoustic oscillation (BAO) peak in the
redshift-space correlation function yield the angular diameter distance D_A(z)
and the Hubble parameter H(z) as a function of redshift, constraining the
properties of dark energy and space curvature. We discuss the perturbations
introduced in the galaxy correlation function by gravitational lensing through
the effect of magnification bias and its cross-correlation with the galaxy
density. At the BAO scale, gravitational lensing adds a small and slowly
varying component to the galaxy correlation function and does not change its
shape significantly, through which the BAO peak is measured. The relative shift
in the position of the BAO peak caused by gravitational lensing in the
angle-averaged correlation function is 10^-4 at z=1, rising to 10^-3 at z=2.5.
Lensing effects are stronger near the line-of-sight, however the relative peak
shift increases only to 10^-3.3 and 10^-2.4 at z=1 and z=2.5, when the galaxy
correlation is averaged within 5 degrees of the line-of-sight (containing only
0.4% of the galaxy pairs in a survey). Furthermore, the lensing contribution
can be measured separately and subtracted from the observed correlation at the
BAO scale.
