Renormalizing one-point probability distribution function for cosmological counts in cells
Abstract
We study the one-point probability distribution function (PDF) for matter
density averaged over spherical cells. The leading part to the PDF is defined
by spherical collapse dynamics, whereas the next-to-leading part comes from the
integration over fluctuations around the saddle-point solution. The latter
calculation receives sizable contributions from short modes and must be
renormalized. We propose a new approach to renormalization by modeling the
effective stress-energy tensor for short perturbations. The model contains
three free parameters. Two of them are related to the counterterms in the
one-loop matter power spectrum and bispectrum, one more parameterizes their
redshift dependence. This relation can be used to impose priors in fitting the
model to the PDF data. We confront the model with the results of
high-resolution N-body simulations and find excellent agreement for cell radii
$r_*\geq 10\,{\rm Mpc}/h$ at all redshifts down to $z=0$. Discrepancies at a
few per cent level are detected at low redshifts for $r_*\leq 10\,{\rm Mpc}/h$
and are associated with two-loop corrections to the model.