TY - JOUR
T1 - Non-Gaussian initial conditions in ΛCDM
T2 - Newtonian, relativistic, and primordial contributions
AU - Bruni, Marco
AU - Carlos Hidalgo, Juan
AU - Meures, Nikolai
AU - Wands, David
N1 - Copyright 2014. The American Astronomical Society.
PY - 2014/4/10
Y1 - 2014/4/10
N2 - The goal of the present paper is to set initial conditions for structure formation at nonlinear order, consistent
with general relativity, while also allowing for primordial non-Gaussianity. We use the nonlinear continuity and
Raychaudhuri equations, which together with the nonlinear energy constraint, determine the evolution of the
matter density fluctuation in general relativity. We solve this equations at first and second order in a perturbative
expansion, recovering and extending previous results derived in the matter-dominated limit and in the Newtonian regime. We present a second-order solution for the comoving density contrast in a ΛCDM universe, identifying
nonlinear contributions coming from the Newtonian growing mode, primordial non-Gaussianity and intrinsic non-
Gaussianity, due to the essential nonlinearity of the relativistic constraint equations. We discuss the application
of these results to initial conditions in N-body simulations, showing that relativistic corrections mimic a non-zero
nonlinear parameter fNL.
AB - The goal of the present paper is to set initial conditions for structure formation at nonlinear order, consistent
with general relativity, while also allowing for primordial non-Gaussianity. We use the nonlinear continuity and
Raychaudhuri equations, which together with the nonlinear energy constraint, determine the evolution of the
matter density fluctuation in general relativity. We solve this equations at first and second order in a perturbative
expansion, recovering and extending previous results derived in the matter-dominated limit and in the Newtonian regime. We present a second-order solution for the comoving density contrast in a ΛCDM universe, identifying
nonlinear contributions coming from the Newtonian growing mode, primordial non-Gaussianity and intrinsic non-
Gaussianity, due to the essential nonlinearity of the relativistic constraint equations. We discuss the application
of these results to initial conditions in N-body simulations, showing that relativistic corrections mimic a non-zero
nonlinear parameter fNL.
KW - cosmology: theory
KW - dark matter
KW - large-scale structure of universe
U2 - 10.1088/0004-637X/785/1/2
DO - 10.1088/0004-637X/785/1/2
M3 - Article
SN - 0004-637X
VL - 785
JO - The Astrophysical Journal
JF - The Astrophysical Journal
IS - 1
ER -