The redshift-space galaxy two-point correlation function and baryon
  acoustic oscillations
  Future galaxy surveys will measure baryon acoustic oscillations (BAOs) with
high significance, and a complete understanding of the anisotropies of BAOs in
redshift space will be important to exploit the cosmological information in
BAOs. Here we describe the anisotropies that arise in the redshift-space galaxy
two-point correlation function (2PCF) and elucidate the origin of features that
arise in the dependence of the BAOs on the angle between the orientation of the
galaxy pair and the line of sight. We do so with a derivation of the
configuration-space 2PCF using streaming model. We find that, contrary to
common belief, the locations of BAO peaks in the redshift-space 2PCF are
anisotropic even in the linear theory. Anisotropies in BAO depend strongly on
the method of extracting the peak, showing maximum 3 % angular variation. We
also find that extracting the BAO peak of $r^2\xi(r,\mu)$ significantly reduces
the anisotropy to sub-percent level angular variation. When subtracting the
tilt due to the broadband behavior of the 2PCF, the BAO bump is enhanced along
the line of sight because of local infall velocities toward the BAO bump.
Precise measurement of the angular dependence of the redshift-space 2PCF will
allow new geometrical tests of dark energy beyond the BAO.
