Cosmological <i>N</i>-Body Simulations

Bertschinger, Edmund; Gelb, James M.

doi:10.1063/1.4822978

Cited by 172 publications

(178 citation statements)

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“…A large number of groups have therefore developed N-body codes for collisionless dynamics that compute the large-scale gravitational field by means of Fourier techniques. These are the PM, P 3 M, and AP 3 M codes (Eastwood & Hockney 1974;Hohl 1978;Hockney & Eastwood 1981;Efstathiou et al 1985;Couchman 1991;Bertschinger & Gelb 1991;MacFarland et al 1998). Modern versions of these codes supplement the force computation on scales below the mesh size with a direct summation, and/or they place mesh refinements on highly clustered regions.…”

Section: Introductionmentioning

confidence: 99%

GADGET: a code for collisionless and gasdynamical cosmological simulations

2001

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We describe the newly written code GADGET which is suitable both for cosmological simulations of structure formation and for the simulation of interacting galaxies. GADGET evolves self-gravitating collisionless fluids with the traditional N-body approach, and a collisional gas by smoothed particle hydrodynamics. Along with the serial version of the code, we discuss a parallel version that has been designed to run on massively parallel supercomputers with distributed memory. While both versions use a tree algorithm to compute gravitational forces, the serial version of GADGET can optionally employ the special-purpose hardware GRAPE instead of the tree. Periodic boundary conditions are supported by means of an Ewald summation technique. The code uses individual and adaptive timesteps for all particles, and it combines this with a scheme for dynamic tree updates. Due to its Lagrangian nature, GADGET thus allows a very large dynamic range to be bridged, both in space and time. So far, GADGET has been successfully used to run simulations with up to 7.5×10 7 particles, including cosmological studies of large-scale structure formation, high-resolution simulations of the formation of clusters of galaxies, as well as workstation-sized problems of interacting galaxies. In this study, we detail the numerical algorithms employed, and show various tests of the code. We publically release both the serial and the massively parallel version of the code.

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Section: Introductionmentioning

confidence: 99%

GADGET: a code for collisionless and gasdynamical cosmological simulations

2001

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“…The Abell clusters were selected using galaxies in a sphere of a radius of about 1.5 h −1 Mpc. Our density field method to find halos is rather similar to the DENMAX method by Bertschinger & Gelb (1991) and Gelb & Bertschinger (1994). The basic difference lies in the detail: we do not use particles to define the center and the mass of the halo, but only data obtained directly from the density field.…”

Section: Comparison Of Halo Findersmentioning

confidence: 99%

The cosmic web for density perturbations of various scales

Suhhonenko

Einasto

Liivamägi

et al. 2011

A&A

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Aims. We follow the evolution of galaxy systems in numerical simulations. Our goal is to understand the role of density perturbations on various scales in the formation and evolution of the cosmic web. Methods. We perform numerical simulations with the full power spectrum of perturbations, and with a spectrum cut at long wavelengths. In addition, we have one model, where we cut the intermediate waves. We analyse the density field and study void sizes and density field clusters in different models. Results. Our analysis shows that the fine structure (groups and clusters of galaxies) are created by small-scale density perturbations of scale ≤8 h −1 Mpc. Filaments of galaxies and clusters are created by perturbations of intermediate scale from ∼8 to ∼32 h −1 Mpc, and superclusters of galaxies by larger perturbations. Conclusions. We conclude that the texture of the cosmic web is determined by density perturbations of the scales up to ∼100 h −1 Mpc. Larger perturbations do not change the texture of the web, but modulate the richness of galaxy systems, and make voids emptier.

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“…The most widely used halo-finding algorithm called the friends-of-friends algorithm (e.g., Davis et al 1985) and the spherical overdensity algorithm (Cole & Lacey 1994, Navarro, Frenk, & White 1996 are not acceptable (Bertschinger & Gelb 1991), because they cannot separate substructures within large halos.…”

Section: Halo Identificationmentioning

confidence: 99%

Formation and Evolution of Galactic Halos in Clusters of Galaxies

Okamoto

Habe

1999

Numerical Astrophysics

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We investigate effects of time evolution of a rich cluster of galaxies on its member galactic halos in the standard cold dark matter (SCDM) universe using high resolution N-body simulations. We identify several hundred galactic halos within virial radius of our simulated cluster. We also find that a large number of halos have been tidally disrupted at z = 0. Therefore we improve a method of deriving merging history trees of galaxies taking account of tidally stripped galaxies.The main results are as follows: (1) At high redshift (z ≃ 2), the mass function of the galactic halos which are in the cluster at z = 0 is very similar to that obtained in the field region and well agrees with the Press-Schechter mass function. (2) The mass function of cluster galaxies which consist of both galactic halos and tidally stripped galaxies has hardly evolved since z ≃ 2. This mass function at z = 0 is well represented by the Press-Schechter mass function at z = 2. (3) At high redshift (z > 3), in the region which becomes the cluster the fraction of galaxies which have undergone recent merger is lager than that in the field. After z ∼ 3, however, it rapidly decreases and becomes smaller than that in the field. (4) The strongly stripped galaxy fraction of the cluster galaxies begins to increase from z ≃ 0.5. At z = 0, a clear correlation appears between this fraction and the distance from the center of the cluster. (5) Tidally truncated halos have steeper outer profiles than those of the model

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Cosmological N-Body Simulations

Cited by 172 publications

References 0 publications

GADGET: a code for collisionless and gasdynamical cosmological simulations

GADGET: a code for collisionless and gasdynamical cosmological simulations

The cosmic web for density perturbations of various scales

Formation and Evolution of Galactic Halos in Clusters of Galaxies

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