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We describe a new hybrid N-body/hydrodynamical code based on the particle-mesh (PM) method and the piecewise-parabolic method (PPM) for use in solving problems related to the evolution of large-scale structure, galaxy clusters, and…

Astrophysics · Physics 2009-10-31 P. M. Ricker , S. Dodelson , D. Q. Lamb

We present results of tests of the evolution of small ``fluid elements'' in cosmological N--body simulations, to examine the validity of their treatment as particles. We find that even very small elements typically collapse along one axis…

Astrophysics · Physics 2009-10-28 B. Kuhlman , A. L. Melott , S. F. Shandarin

Gas-poor galaxies can be modelled as composite collisionless stellar systems, with a dark matter halo and one or more stellar components, representing different stellar populations. The dynamical evolution of such composite systems is often…

Astrophysics of Galaxies · Physics 2021-03-24 Carlo Nipoti , Giacomo Cherchi , Giuliano Iorio , Francesco Calura

We present $\Lambda$CDM $N$-body cosmological simulations in the framework of a static general scalar-tensor theory of gravity. Due to the influence of the non-minimally coupled scalar field, the gravitational potential is modified by a…

The stability of a galaxy model is most easily assessed through N-body simulation. Particle-mesh codes have been widely used for this purpose, since they enable the largest numbers of particles to be employed. We show that the functional…

Astrophysics · Physics 2009-10-28 David J. D. Earn , J. A. Sellwood

We describe the astrophysical and numerical basis of N-body simulations, both of collisional stellar systems (dense star clusters and galactic centres) and collisionless stellar dynamics (galaxies and large-scale structure). We explain and…

Instrumentation and Methods for Astrophysics · Physics 2011-05-26 Walter Dehnen , Justin Read

Cosmological $N$-body simulations are typically purely run with particles using Newtonian equations of motion. However, such simulations can be made fully consistent with general relativity using a well-defined prescription. Here, we extend…

Cosmology and Nongalactic Astrophysics · Physics 2019-03-20 Thomas Tram , Jacob Brandbyge , Jeppe Dakin , Steen Hannestad

Using controlled numerical N-body experiments, we show how, in the collapse dynamics of an initially cold and uniform distribution of particles with a generic asymmetric shape, finite $N$ fluctuations and perturbations induced by the…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-11 Francesco Sylos Labini , Michael Joyce

We examine the cosmological redshift-space distortion effect on the power spectrum of the objects at high-redshifts, which is an unavoidable observational contamination in general relativistic cosmology. In particular, we consider the…

Astrophysics · Physics 2009-10-31 Hiromitsu Magira , Y. P. Jing , Yasushi Suto

We introduce a new code, ECOSMOG, to run N-body simulations for a wide class of modified gravity and dynamical dark energy theories. These theories generally have one or more new dynamical degrees of freedom, the dynamics of which are…

Cosmology and Nongalactic Astrophysics · Physics 2012-07-04 Baojiu Li , Gong-Bo Zhao , Romain Teyssier , Kazuya Koyama

We present the results of cosmological simulations of large-scale structure formation with massive neutrinos. The phase-space distribution of the cosmic relic neutrinos is followed, for the first time, by directly integrating the…

Cosmology and Nongalactic Astrophysics · Physics 2020-12-09 Kohji Yoshikawa , Satoshi Tanaka , Naoki Yoshida , Shun Saito

Beyond convergence studies and comparison of different codes, there are essentially no controls on the accuracy in the non-linear regime of cosmological N body simulations, even in the dissipationless limit. We propose and explore here a…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-30 Michael Joyce , Francesco Sylos Labini

We present the first calculation of an intrinsically relativistic quantity in fully non-linear cosmolog- ical large-scale structure studies. Traditionally, non-linear structure formation in standard {\Lambda}CDM cosmology is studied using…

Cosmology and Nongalactic Astrophysics · Physics 2014-02-26 Marco Bruni , Daniel B. Thomas , David Wands

In this paper we present preliminary results from cosmological simulations of modified gravity in the dark matter sector. Our results show improvements over standard cold dark matter cosmology. The abundance of low-mass haloes in the…

Astrophysics · Physics 2008-07-08 Wojciech A. Hellwing

We report on the results of a study of the motion of a four particle non-relativistic one-dimensional self-gravitating system. We show that the system can be visualized in terms of a single particle moving within a potential whose…

General Relativity and Quantum Cosmology · Physics 2013-06-18 Andrew Laurtizen , Peter Gustainis , Robert B. Mann

Future large-scale structure surveys of the Universe will aim to constrain the cosmological model and the true nature of dark energy with unprecedented accuracy. In order for these surveys to achieve their designed goals, they will require…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Robert E. Smith , Darren S. Reed , Doug Potter , Laura Marian , Martin Crocce , Ben Moore

The standard numerical tools for studying non-linear collapse of matter are Newtonian $N$-body simulations. Previous work has shown that these simulations are in accordance with General Relativity (GR) up to first order in perturbation…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-07 Christian Fidler , Thomas Tram , Cornelius Rampf , Robert Crittenden , Kazuya Koyama , David Wands

We present the results of a novel type of numerical simulation that realizes a rotating Universe with a shear-free, rigid body rotation inspired by a G\"{o}del-like metric. We run cosmological simulations of unperturbed glasses with various…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-03 Balázs Pál , Tze Goh , Gábor Rácz , István Szapudi

We present numerical $N$-body simulation studies of large-scale structure formation. The main purpose of these studies is to analyze the several models of dark matter and the role they played in the process of large-scale structure…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-22 M. A. Rodriguez-Meza

We study the accumulation of errors in cosmological N-body algorithms that are caused by representing the continuous distribution of matter by massive particles, comparing the PPPM and Adaptive Multigrid codes. We use for this a new measure…

Astrophysics · Physics 2007-05-23 Ivar Suisalu , Enn Saar