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We train convolutional neural networks to correct the output of fast and approximate N-body simulations at the field level. Our model, Neural Enhanced COLA --NECOLA--, takes as input a snapshot generated by the computationally efficient…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-18 Neerav Kaushal , Francisco Villaescusa-Navarro , Elena Giusarma , Yin Li , Conner Hawry , Mauricio Reyes

We present a novel, highly efficient algorithm to parallelize O(N^2) direct summation method for N-body problems with individual timesteps on distributed-memory parallel machines such as Beowulf clusters. Previously known algorithms, in…

Astrophysics · Physics 2009-11-07 Junichiro Makino

We present the first detailed comparison between million-body globular cluster simulations computed with a H\'enon-type Monte Carlo code, CMC, and a direct $N$-body code, NBODY6++GPU. Both simulations start from an identical cluster model…

Instrumentation and Methods for Astrophysics · Physics 2016-08-31 Carl L. Rodriguez , Meagan Morscher , Long Wang , Sourav Chatterjee , Frederic A. Rasio , Rainer Spurzem

We present a comparison of major methodologies of fast generating mock halo or galaxy catalogues. The comparison is done for two-point and the three-point clustering statistics. The reference catalogues are drawn from the BigMultiDark…

(Abridged) The growing role played by numerical N-body simulations in cosmological studies as a fundamental connection between theoretical modeling and direct observations has led to impressive advancements also in the development and…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-26 Marco Baldi

We present a suite of cosmological N-body simulations with cold dark matter and baryons aiming at modeling the low-density regions of the IGM as probed by the Lyman-$\alpha$ forests at high redshift. The simulations are designed to match…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 A. Borde , N. Palanque-Delabrouille , G. Rossi , M. Viel , J. Bolton , Ch. Yèche , J. -M. LeGoff , J. Rich

Quantum computers can efficiently simulate many-body systems. As a widely used Hamiltonian simulation tool, the Trotter-Suzuki scheme splits the evolution into the number of Trotter steps $N$ and approximates the evolution of each step by a…

Quantum Physics · Physics 2019-01-23 Suguru Endo , Qi Zhao , Ying Li , Simon Benjamin , Xiao Yuan

The TREE method has been widely used for long-range interaction {\it N}-body problems. We have developed a parallel TREE code for two-component classical plasmas with open boundary conditions and highly non-uniform charge distributions. The…

Computational Physics · Physics 2009-05-04 Byoungseon Jeon , Joel D. Kress , Lee A. Collins , Niels Grønbech-Jensen

The gravitationally-driven evolution of cold dark matter dominates the formation of structure in the Universe over a wide range of length scales. While the longest scales can be treated by perturbation theory, a fully quantitative…

Astrophysics · Physics 2009-11-10 Katrin Heitmann , Paul M. Ricker , Michael S. Warren , Salman Habib

Gravitational $N$-body simulations calculate numerous interactions between particles. The tree algorithm reduces these calculations by constructing a hierarchical oct-tree structure and approximating gravitational forces on particles. Over…

Instrumentation and Methods for Astrophysics · Physics 2024-01-09 Tomoyuki Tokuue , Tomoaki Ishiyama

Despite the recent advances in graphics hardware capabilities, a brute force approach is incapable of interactively displaying terabytes of data. We have implemented a system that uses hierarchical level-of-detailing for the results of…

Graphics · Computer Science 2008-11-18 Tamas Szalay , Volker Springel , Gerard Lemson

We present performance measurements of direct gravitational N -body simulation on the grid, with and without specialized (GRAPE-6) hardware. Our inter-continental virtual organization consists of three sites, one in Tokyo, one in…

Astrophysics · Physics 2008-11-26 Derek Groen , Simon Portegies Zwart , Steve McMillan , Jun Makino

The Quijote simulations are a set of 44,100 full N-body simulations spanning more than 7,000 cosmological models in the $\{\Omega_{\rm m}, \Omega_{\rm b}, h, n_s, \sigma_8, M_\nu, w \}$ hyperplane. At a single redshift the simulations…

Modelling the cosmic large-scale structure can be done through numerical N-body simulations or by using perturbation theory. Here, we present an N-body approach that effectively implements a multi-step forward model based on Lagrangian…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-13 Cornelius Rampf , Florian List , Oliver Hahn

Analysis of large galaxy surveys requires confidence in the robustness of numerical simulation methods. The simulations are used to construct mock galaxy catalogs to validate data analysis pipelines and identify potential systematics. We…

We present an implementation of the hierarchical tree algorithm on the individual timestep algorithm (the Hermite scheme) for collisional $N$-body simulations, running on GRAPE-9 system, a special-purpose hardware accelerator for…

Instrumentation and Methods for Astrophysics · Physics 2016-03-23 Toshiyuki Fukushige , Atsushi Kawai

In the last decades cosmological N-body dark matter simulations have enabled ab initio studies of the formation of structure in the Universe. Gravity amplified small density fluctuations generated shortly after the Big Bang, leading to the…

Instrumentation and Methods for Astrophysics · Physics 2016-11-18 Ralf Kaehler , Oliver Hahn , Tom Abel

Small- and intermediate-scale galaxy clustering can be used to establish the galaxy-halo connection to study galaxy formation and evolution and to tighten constraints on cosmological parameters. With the increasing precision of galaxy…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-23 Zheng Zheng , Hong Guo

We present a new N-body and gas dynamics code, called Nyx, for large-scale cosmological simulations. Nyx follows the temporal evolution of a system of discrete dark matter particles gravitationally coupled to an inviscid ideal fluid in an…

Instrumentation and Methods for Astrophysics · Physics 2015-06-12 Ann Almgren , John Bell , Mike Lijewski , Zarija Lukić , Ethan Van Andel

A major goal of computational astrophysics is to simulate the Milky Way Galaxy with sufficient resolution down to individual stars. However, the scaling fails due to some small-scale, short-timescale phenomena, such as supernova explosions.…