Transients from initial conditions in cosmological simulations

By Martín Crocce, Sebastian Pueblas, R. Scoccimarro. 2006

552 citations recorded by the source corpus.

We study the impact of setting initial conditions in numerical simulations using the standard procedure based on the Zel'dovich approximation (ZA). As it is well known from the perturbation theory, ZA initial conditions have incorrect second- and higher-order growth and therefore excite long-lived transients in the evolution of the statistical properties of density and velocity fields. We also study the improvement brought by using more accurate initial conditions based on second-order Lagrangian perturbation theory (2LPT). We show that 2LPT initial conditions reduce transients significantly and thus are much more appropriate for numerical simulations devoted to precision cosmology. Using controlled numerical experiments with ZA and 2LPT initial conditions, we show that simulations started at redshift z i = 49 using the ZA underestimate the power spectrum in the non-linear regime by about 2,4 and 8 per cent at z = 0, 1, and 3, respectively, whereas the mass function of dark matter haloes is underestimated by 5 per cent at m = 10 15 M ⊙ h -1 (z = 0) and 10 per cent at m = 2 × 10 14 M ⊙ h - (z = 1). The clustering of haloes is also affected to the few per cent level at z = 0. These systematics effects are typically larger than statistical uncertainties in recent mass function and power spectrum fitting formulae extracted from numerical simulations. At large scales, the measured transients in higher-order correlations can be understood from first principle calculations based on perturbation theory.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/a6f3999163287438203d7a02d93201009b401656

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Citations in the corpus

Halo mass function and the free streaming scale (2013, methodology): “For the initial conditions we used the 2LPT code (Scoccimarro 1998; Crocce et al. 2006) with an initial redshift of zIC = 49 for runs with box size L = 256 h−1Mpc and zIC = 99 for runs with box sizes L = 64 h−1Mpc and L = 16 h−1Mpc.”
A UNIVERSAL MODEL FOR HALO CONCENTRATIONS (2014, methodology): “The initial conditions for the simulations were generated using the second-order Lagrangian perturbation theory code 2LPTic (Crocce et al. 2006).”
Gravity and Large-Scale Nonlocal Bias (2012, methodology): “The simulations were run using Gadget2 [77] with initial conditions set at zi = 49 using 2nd order-Lagrangian Perturbation Theory (2LPT) [49, 78].”
The detectability of baryonic acoustic oscillations in future galaxy surveys. (2007, methodology): “The Zel’dovich (1970) approximation used to set up the initial pattern of density fluctuations produces transients which can be seen in clustering signal measured for the dark matter at expansion factors close to the starting redshift (Efstathiou et al. 1985; Baugh et al. 1995; Crocce et al. 2006).”
THE AVERAGE STAR FORMATION HISTORIES OF GALAXIES IN DARK MATTER HALOS FROM z = 0–8 (2012, result): “The Zel’dovich approximation has been previously found to underestimate the early nonlinear collapse of overdense regions (Crocce et al. 2006; Jenkins 2010), which is reconfirmed by the comparison in Fig.”
The Quijote Simulations (2019, methodology): “Generating the initial conditions via Zel’dovich, instead of 2LPT, can induce small changes in the dynamics of the simulation particles, that can lead to small statistical differences (Crocce et al. 2006).”
THE MASS SPECTRUM OF THE FIRST STARS (2014, methodology): “The initial conditions are generated by 2LPT code, in which the second-order Lagrangian perturbation theory is used (Crocce et al. 2006), and all the simulations are initialized at z = 200.”
Scaling relations for galaxy clusters in the Millennium-XXL simulation (2012, background): “The latter modification is particularly important for the present study, since the abundance of high mass haloes is sensitive to initial transients, which are much smaller and decay more quickly when 2LPT is used (Crocce et al. 2006).”
The Halo Mass Function: High-Redshift Evolution and Universality (2007, methodology): “It has been explored in the context of simulation error by Valageas (2002) and by Crocce et al. (2006).”
The bispectrum in the Effective Field Theory of Large Scale Structure (2014, methodology): “The initial conditions are set up at redshift z = 99 using a second order Lagrangian perturbation theory code 2LPT [33] and the subsequent gravitational evolution is computed using the Tree-PM code Gadget-II [34].”
Matter power spectrum and the challenge of percent accuracy (2015, methodology): “…to use second order Lagrangian perturbation theory (2LPT) with respect to the simpler first order or Zel’dovich approximation (ZA), as it allows for smaller starting redshifts, further away form the noise dominated high-redshift regime (Crocce et al. 2006; Jenkins 2010; Reed et al. 2013).”
REVISING THE HALOFIT MODEL FOR THE NONLINEAR MATTER POWER SPECTRUM (2012, methodology): “We generate the initial conditions based on the second-order Lagrangian perturbation theory (2LPT; Crocce et al. 2006; Nishimichi et al. 2009) with the initial linear power spectrum calculated by the Code for Anisotropies in the Microwave Background (CAMB; Lewis et al. 2000).”
The MICE Grand Challenge Lightcone Simulation I: Dark matter clustering (2013, background): “However we have estimated this to be a 1% effect in the k-range 0.5 − 1hMpc−1 for the redshifts shown (using PT, see Crocce et al. (2006)).”