New fitting formula for cosmic non-linear density distribution
  We have measured the probability distribution function (PDF) of cosmic matter
density field from a suite of N-body simulations. We propose the generalized
normal distribution of version 2 (Nv2) as an alternative fitting formula to the
well-known log-normal distribution. We find that Nv2 provides significantly
better fit than the log-normal distribution for all smoothing radii (2, 5, 10,
25 [Mpc/h]) that we studied. The improvement is substantial in the underdense
regions. The development of non- Gaissianities in the cosmic matter density
field is captured by continuous evolution of the skewness and shifts parameters
of the Nv2 distribution. We present the redshift evolution of these parameters
for aforementioned smoothing radii and various background cosmology models. All
the PDFs measured from large and high-resolution N-body simulations that we use
in this study can be obtained from a Web site at
https://astro.kias.re.kr/jhshin.
