Redshift Space Distortion Reconstruction
  Redshift space distortions of the matter density power spectrum carry
information on the growth rate of cosmic structure but require accurate
modeling of nonlinear and velocity effects on the density field. We test and
advance the reconstruction function of Kwan, Lewis, Linder (2012) in several
ways. First, we compare to the distribution function perturbative approach of
Seljak & McDonald (2012), deriving the mapping between them and showing how the
KLL form can extend the validity of the latter. Second, using cosmological
simulations rather than perturbation theory we calibrate the free functions
within the KLL reconstruction form and fit their behavior in redshift and
wavenumber. An efficient, new analysis pipeline rapidly calculates from
simulation outputs the redshift space power spectrum. The end result is a
robust analytic reconstruction function mapping the linear, real space matter
power spectrum to the nonlinear, anisotropic redshift space power spectrum to
an accuracy of ~2-5% in the range k=0.1-0.5 h/Mpc for z=0-2. As a by-product we
derive RealEasy, an analytic mapping to the nonlinear, real space matter power
spectrum (i.e. an analog to Halofit) to ~1% accuracy over the same range. We
also investigate an approach converse to KLL and find it to be complementary
and capable of achieving an accuracy of ~2-4% over the range k=0.3-1 h/Mpc for
z=0-2.
