Hybrid modeling of redshift space distortions
  The observed power spectrum in redshift space appears distorted due to the
peculiar motion of galaxies, known as redshift-space distortions (RSD). While
all the effects in RSD are accounted for by the simple mapping formula from
real to redshift spaces, accurately modeling redshift-space power spectrum is
rather difficult due to the non-perturbative properties of the mapping. Still,
however, a perturbative treatment may be applied to the power spectrum at
large-scales, and on top of a careful modeling of the Finger-of-God effect
caused by the small-scale random motion, the redshift-space power spectrum can
be expressed as a series of expansion which contains the higher-order
correlations of density and velocity fields. In our previous work [JCAP 8
(Aug., 2016) 050], we provide a perturbation-theory inspired model for power
spectrum in which the higher-order correlations are evaluated directly from the
cosmological $N$-body simulations. Adopting a simple Gaussian ansatz for
Finger-of-God effect, the model is shown to quantitatively describe the
simulation results. Here, we further push this approach, and present an
accurate power spectrum template which can be used to estimate the growth of
structure as a key to probe gravity on cosmological scales. Based on the
simulations, we first calibrate the uncertainties and systematics in the
pertrubation theory calculation in a fiducial cosmological model. Then, using
the scaling relations, the calibrated power spectrum template is applied to a
different cosmological model. We demonstrate that with our new template, the
best-fitted growth functions are shown to reproduce the fiducial values in a
good accuracy of 1 \% at $k<0.18 \hompc$ for cosmologies with different Hubble
parameters.
