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We present a new time-stepping criterion for N-body simulations that is based on the true dynamical time of a particle. This allows us to follow the orbits of particles correctly in all environments since it has better adaptivity than…

Astrophysics · Physics 2009-10-12 Marcel Zemp , Joachim Stadel , Ben Moore , C. Marcella Carollo

In this paper, we present the density, \rho, velocity dispersion, \sigma, and \rho/\sigma^3 profiles of isotropic systems which have the energy distribution, N(E)\propto[\exp(\phi_0-E)-1], derived in Paper I. This distribution, dubbed…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Liliya L. R. Williams , Jens Hjorth

Thin stellar discs on both galactic and nuclear, sub-kpc scales are believed to be fragile structures that would be easily destroyed in major mergers. In turn, this makes the age-dating of their stellar populations a useful diagnostics for…

We present the problematic of controlling the discreteness effects in cosmological N-body simulations. We describe a perturbative treatment which gives an approximation describing the evolution under self-gravity of a lattice perturbed from…

Statistical Mechanics · Physics 2009-11-13 B. Marcos

The possible observations of Trojan-like extrasolar planets stimulate the deeper understanding of the stability behaviour of the co-orbital resonant motion. By using Hill's equations and the energy-rate method an analysis of the stability…

Earth and Planetary Astrophysics · Physics 2015-06-15 Tamas Kovacs

We have simulated the formation of a galaxy cluster in a $\Lambda$CDM universe using twelve different codes modeling only gravity and non-radiative hydrodynamics (\art, \arepo, \hydra\ and 9 incarnations of GADGET). This range of codes…

We present a suite of cosmological N-body simulations describing the "Running Friedmann-Lema{\"i}tre-Robertson-Walker" (R-FLRW) cosmological model. This model is based on quantum field theory in a curved space-time and extends {\Lambda}CDM…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-25 Antonio Bibiano , Darren J. Croton

We consider $n$-body problems given by potentials of the form ${\alpha\over r^a}+{\beta\over r^b}$ with $a,b,\alpha,\beta$ constants, $0\le a<b$. To analyze the dynamics of the problem, we first prove some properties related to central…

Mathematical Physics · Physics 2009-09-29 Florin Diacu , Ernesto Perez-Chavela , Manuele Santoprete

We study the orbital structure of a self-consistent N-body equilibrium configuration of a barred galaxy constructed from cosmological initial conditions. The value of its spin parameter L is near the observed value of our Galaxy L=0.22. We…

Astrophysics · Physics 2007-07-31 N. Voglis , M. Harsoula , G. Contopoulos

We investigate the hydrodynamics of the interaction of two supersonic winds in binary systems. The collision of the winds creates two shocks separated by a contact discontinuity. The overall structure depends on the momentum flux ratio eta…

Solar and Stellar Astrophysics · Physics 2015-05-30 Astrid Lamberts , Sebastien Fromang , Guillaume Dubus

Systems with long-range (LR) forces, for which the interaction potential decays with the interparticle distance with an exponent smaller than the dimensionality of the embedding space, remain an outstanding challenge to statistical physics.…

Statistical Mechanics · Physics 2016-03-23 Yan Levin , Renato Pakter , Felipe B. Rizzato , Tarcísio N. Teles , Fernanda P. da C. Benetti

For simulations that deal only with dark matter or stellar systems, the conventional N-body technique is fast, memory efficient, and relatively simple to implement. However when including the effects of gas physics, mesh codes are at a…

Instrumentation and Methods for Astrophysics · Physics 2012-11-21 Nigel L. Mitchell , Eduard I. Vorobyov , Gerhard Hensler

Equilibrium crystal structures, electron band dispersions and band gap values of layered GaSe and InSe semiconductors, each being represented by four polytypes, are studied via first-principles calculations within the density functional…

Materials Science · Physics 2018-08-10 Juliana Srour , Michael Badawi , Fouad El Haj Hassan , Andrei Postnikov

We present N-body simulations of dissolving star clusters close to galactic centres. For this purpose, we developed a new N-body program called nbody6gc based on Aarseth's series of N-body codes. We describe the algorithm in detail. We…

Astrophysics of Galaxies · Physics 2015-05-13 Andreas Ernst , Andreas Just , Rainer Spurzem

This paper concentrates on four key tools for performing star cluster simulations developed during the last decade which are sufficient to handle all the relevant dynamical aspects. First we discuss briefly the Hermite integration scheme…

Astrophysics · Physics 2009-10-31 Sverre J. Aarseth

A new N-body and hydrodynamical code, called RAMSES, is presented. It has been designed to study structure formation in the universe with high spatial resolution. The code is based on Adaptive Mesh Refinement (AMR) technique, with a tree…

Astrophysics · Physics 2014-10-13 Romain Teyssier

The evidence in favor of a dark energy component dominating the Universe, and driving its presently accelerated expansion, has progressively grown during the last decade of cosmological observations. If this dark energy is given by a…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-05 Marco Baldi

Within a cosmological context, we study the behaviour of collisionless particles in the weak field approximation to General Relativity, allowing for large gradients of the fields and relativistic velocities for the particles. We consider a…

Cosmology and Nongalactic Astrophysics · Physics 2016-02-03 Julian Adamek , Mateja Gosenca , Shaun Hotchkiss

An expansion of a density field or particle distribution in basis functions which solve the Poisson equation both provides an easily parallelized n-body force algorithm and simplifies perturbation theories. The expansion converges quickly…

Astrophysics · Physics 2009-10-30 Martin D. Weinberg

Understanding the long-term evolution of hierarchical triple systems is challenging due to its inherent chaotic nature, and it requires computationally expensive simulations. Here we propose a convolutional neural network model to predict…

Solar and Stellar Astrophysics · Physics 2022-10-26 Florian Lalande , Alessandro Alberto Trani
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