Effects of the size of cosmological N-body simulations on physical quantities — II: Halo formation and destruction rate

Prasad, J.

doi:10.1007/s12036-007-0009-3

Cited by 3 publications

(2 citation statements)

References 34 publications

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“…Therefore cosmological simulations need to be run with periodic boundary conditions 1 . The simulation volume should be large enough for the effects of missing modes to be small, (Bagla & Ray 2005;Bagla & Prasad 2006;Power & Knebe 2006;Prasad 2007;Bagla, Prasad, & Khandai 2008).…”

Section: Introductionmentioning

confidence: 99%

The Adaptive TreePM: an adaptive resolution code for cosmologicalN-body simulations

Bagla¹,

Khandai²

2009

Monthly Notices of the Royal Astronomical Society

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Cosmological N‐body simulations are used for a variety of applications. Indeed progress in the study of large‐scale structures and galaxy formation would have been very limited without this tool. For nearly 20 yr the limitations imposed by computing power forced simulators to ignore some of the basic requirements for modelling gravitational instability. One of the limitations of most cosmological codes has been the use of a force softening length that is much smaller than the typical interparticle separation. This leads to departures from collisionless evolution that is desired in these simulations. We propose a particle‐based method with an adaptive resolution where the force softening length is reduced in high‐density regions while ensuring that it remains well above the local interparticle separation. The method, called the Adaptive TreePM (ATreePM), is based on the TreePM code. We present the mathematical model and an implementation of this code, and demonstrate that the results converge over a range of options for parameters introduced in generalizing the code from the TreePM code. We explicitly demonstrate collisionless evolution in collapse of an oblique plane wave. We compare the code with the fixed resolution TreePM code and also an implementation that mimics adaptive mesh refinement methods and comment on the agreement and disagreements in the results. We find that in most respects the ATreePM code performs at least as well as the fixed resolution TreePM in highly overdense regions, from clustering and number density of haloes to internal dynamics of haloes. We also show that the adaptive code is faster than the corresponding high‐resolution TreePM code.

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Section: Introductionmentioning

confidence: 99%

The Adaptive TreePM: an adaptive resolution code for cosmologicalN-body simulations

Bagla¹,

Khandai²

2009

Monthly Notices of the Royal Astronomical Society

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“…The highly anisotropic force is always smaller and affects the evolution of the structures inside cosmological simulations. While earlier work extensively studied the effect of finite simulation volumes Bagla & Prasad (2006); Prasad (2007); Bagla et al (2009), the effects of the gravitational force modified by periodicity has not been thoroughly investigated. We show that these are significant even at box sizes as large as L box ∼ 100h −1 Mpc.…”

Section: Introductionmentioning

confidence: 99%

The anisotropy of the power spectrum in periodic cosmological simulations

Rácz,

Szapudi,

Csabai

et al. 2020

Preprint

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The classical gravitational force on a torus is anisotropic and always lower than Newton's 1/r 2 law. We demonstrate the effects of periodicity in dark matter only N-body simulations of spherical collapse and standard ΛCDM initial conditions. Periodic boundary conditions cause an overall negative and anisotropic bias in cosmological simulations of cosmic structure formation. The effect is most significant when the largest mildly non-linear scales are comparable to the linear size of the simulation box, as often is the case for high-resolution hydrodynamical simulations. Spherical collapse morphs into a shape similar to an octahedron. The anisotropic growth distorts the large-scale ΛCDM dark matter structures. We introduce the direction-dependent power spectrum invariant under the octahedral group of the simulation volume and show that the results break spherical symmetry.

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The anisotropy of the power spectrum in periodic cosmological simulations

Rácz

Szapudi

Csabai

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The classical gravitational force on a torus is anisotropic and always lower than Newton’s 1/r2 law. We demonstrate the effects of periodicity in dark matter only N-body simulations of spherical collapse and standard ΛCDM initial conditions. Periodic boundary conditions cause an overall negative and anisotropic bias in cosmological simulations of cosmic structure formation. The lower amplitude of power spectra of small periodic simulations are a consequence of the missing large scale modes and the equally important smaller periodic forces. The effect is most significant when the largest mildly non-linear scales are comparable to the linear size of the simulation box, as often is the case for high-resolution hydrodynamical simulations. Spherical collapse morphs into a shape similar to an octahedron. The anisotropic growth distorts the large-scale ΛCDM dark matter structures. We introduce the direction-dependent power spectrum invariant under the octahedral group of the simulation volume and show that the results break spherical symmetry.

show abstract

Effects of the size of cosmological N-body simulations on physical quantities — II: Halo formation and destruction rate

Cited by 3 publications

References 34 publications

The Adaptive TreePM: an adaptive resolution code for cosmologicalN-body simulations

The Adaptive TreePM: an adaptive resolution code for cosmologicalN-body simulations

The anisotropy of the power spectrum in periodic cosmological simulations

The anisotropy of the power spectrum in periodic cosmological simulations

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