Effects of the initial conditions on cosmological $N$-body simulations

Abstract

Cosmology is entering an era of percent level precision due to current large observational surveys. This precision in observation is now demanding more accuracy from numerical methods and cosmological simulations. In this paper, we study the accuracy of $N$-body numerical simulations and their dependence on changes in the initial conditions and in the simulation algorithms. For this purpose, we use a series of cosmological $N$-body simulations with varying initial conditions. We test the influence of the initial conditions, namely the pre-initial configuration (preIC), the order of the Lagrangian perturbation theory (LPT), and the initial redshift, on the statistics associated with the large scale structures of the universe such as the halo mass function, the density power spectrum, and the maximal extent of the large scale structures. We find that glass or grid pre-initial conditions give similar results at $z\lesssim 2$. However, the initial excess of power in the glass initial conditions yields a subtle difference in the power spectra and the mass function at high redshifts. The LPT order used to generate the ICs of the simulations is found to play a crucial role. First-order LPT (1LPT) simulations underestimate the number of massive haloes with respect to second-order (2LPT) ones, typically by 2% at $10^{14}{h}^{-1}{M}_{\odot }$ for an initial redshift of 23, and the small-scale power with an underestimation of 6% near the Nyquist frequency for $z_{\mathrm{ini}}=23$. Moreover, at higher redshifts, the high-mass end of the mass function is significantly underestimated in 1LPT simulations. On the other hand, when the LPT order is fixed, the starting redshift has a systematic impact on the low-mass end of the halo mass function.

Accepted for publication in New Astronomy, 13 pages

References in corpus (11)

• Transients from Initial Conditions in Cosmological Simulations
• Effects of Baryons and Dissipation on the Matter Power Spectrum
• Building Merger Trees from Cosmological N-body Simulations
• Discreteness effects in simulations of Hot/Warm dark matter
• The Halo Mass Function: High-Redshift Evolution and Universality
• Accurate estimators of power spectra in N-body simulations
• The Structure of Halos: Implications for Group and Cluster Cosmology
• An ideal mass assignment scheme for measuring the Power Spectrum with FFTs
• Evidence for Morphology and Luminosity Transformation of Galaxies at High Redshifts
• Tracing the Mass Growth and Star Formation Rate Evolution of Massive Galaxies from z~6 to z~1 in the Hubble Ultra-Deep Field
• An alternative to grids and glasses: Quaquaversal pre-initial conditions for N-body simulations

Cited by in corpus (31)

• AbacusSummit: A Massive Set of High-Accuracy, High-Resolution $N$-Body Simulations
• Matter power spectrum and the challenge of percent accuracy
• Accurate initial conditions for cosmological N-body simulations: Minimizing truncation and discreteness errors
• Initial Conditions for Accurate N-Body Simulations of Massive Neutrino Cosmologies
• The Horizon Run 5 Cosmological Hydrodynamic Simulation: Probing Galaxy Formation from Kilo- to Giga-parsec Scales
• Horizon Run 4 Simulation: Coupled Evolution of Galaxies and Large-scale Structures of the Universe
• Improving Initial Conditions for Cosmological $N$-Body Simulations
• The Importance of Quantum Pressure of Fuzzy Dark Matter on Lyman-Alpha Forest
• Cosmological constraints from the redshift dependence of the Alcock-Paczynski effect: application to the SDSS-III BOSS DR12 galaxies
• Formation and Morphology of the First Galaxies in the Cosmic Morning
• Probing features in the primordial perturbation spectrum with large-scale structure data
• A question of separation: disentangling tracer bias and gravitational nonlinearity with counts-in-cells statistics
• Cylinders out of a top hat: counts-in-cells for projected densities
• New fitting formula for cosmic non-linear density distribution
• Systematic Effects on the Genus Topology of Large Scale Structure of the Universe
• Simulating Hydrodynamics in Cosmology with CRK-HACC
• Cosmological Parameter Estimation from the Two-Dimensional Genus Topology -- Measuring the Expansion History using the Genus Amplitude as a Standard Ruler
• Topology of Large-Scale Structures of Galaxies in Two Dimensions - Systematic Effects
• Cosmological Parameter Estimation from the Two-Dimensional Genus Topology -- Measuring the Shape of the Matter Power Spectrum
• The ecology of dark matter haloes I: The rates and types of halo interactions
• Resolution Convergence in Cosmological Hydrodynamical Simulations Using Adaptive Mesh Refinement
• Ecology of dark matter haloes -II. Effects of interactions on the alignment of halo pairs
• Numerical convergence of pre-initial conditions on dark matter halo properties
• Impacts of pre-initial conditions on anisotropic separate universe simulations: a boosted tidal response in the epoch of reionization
• Approximate methods for the generation of dark matter halo catalogs in the age of precision cosmology
• On the origin of transient features in cosmological N-Body Simulations
• The Effect of Corner Modes in the Initial Conditions of Cosmological Simulations
• Star-formation Properties of z ~ 1 Galaxy Clusters and Groups from Horizon Run 5
• Efficiency of parallel computations of gravitational forces by TreeCode method in N-body models
• Emergence of the Galaxy Morphology-Star Formation Activity-Clustercentric Radius Relations in Galaxy Clusters
• Particle loads for cosmological simulations with equal-mass dark matter and baryonic particles