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We present a new high-resolution N-body algorithm for cosmological simulations. The algorithm employs a traditional particle-mesh technique on a cubic grid and successive multilevel relaxations on the finer meshes, introduced recursively in…

Astrophysics · Physics 2009-10-30 Andrey V. Kravtsov , Anatoly A. Klypin , Alexei M. Khokhlov

We present a novel, fast and precise method for including the effect of light neutrinos in cosmological N-body simulations. The effect of the neutrino component is included by using the linear theory neutrino perturbations in the…

Astrophysics · Physics 2010-04-15 Jacob Brandbyge , Steen Hannestad

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

N-body simulations are essential tools in physical cosmology to understand the large-scale structure (LSS) formation of the Universe. Large-scale simulations with high resolution are important for exploring the substructure of universe and…

Computational Physics · Physics 2020-10-22 Shenggan Cheng , Hao-Ran Yu , Derek Inman , Qiucheng Liao , Qiaoya Wu , James Lin

We use the emulation framework CosmoPower to construct and publicly release neural network emulators of cosmological observables, including the Cosmic Microwave Background (CMB) temperature and polarization power spectra, matter power…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-06 Boris Bolliet , Alessio Spurio Mancini , J. Colin Hill , Mathew Madhavacheril , Hidde T. Jense , Erminia Calabrese , Jo Dunkley

We present methods for emulating the matter power spectrum by combining information from cosmological $N$-body simulations at different resolutions. An emulator allows estimation of simulation output by interpolating across the parameter…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-17 Ming-Feng Ho , Simeon Bird , Christian R. Shelton

We train a neural network model to predict the full phase space evolution of cosmological N-body simulations. Its success implies that the neural network model is accurately approximating the Green's function expansion that relates the…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-16 Drew Jamieson , Yin Li , Siyu He , Francisco Villaescusa-Navarro , Shirley Ho , Renan Alves de Oliveira , David N. Spergel

The set-up of the initial conditions in cosmological N-body simulations is usually implemented by rescaling the desired low-redshift linear power spectrum to the required starting redshift consistently with the Newtonian evolution of the…

Cosmology and Nongalactic Astrophysics · Physics 2017-01-18 Matteo Zennaro , Julien Bel , Francisco Villaescusa-Navarro , Carmelita Carbone , Emiliano Sefusatti , Luigi Guzzo

One of the most significant challenges involved in efforts to understand the effects of repeated earthquake cycle activity are the computational costs of large-scale viscoelastic earthquake cycle models. Computationally intensive…

Geophysics · Physics 2017-05-03 Phoebe R. DeVries , T. Ben Thompson , Brendan J. Meade

Cosmologists aim to model the evolution of initially low amplitude Gaussian density fluctuations into the highly non-linear "cosmic web" of galaxies and clusters. They aim to compare simulations of this structure formation process with…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-05 Renan Alves de Oliveira , Yin Li , Francisco Villaescusa-Navarro , Shirley Ho , David N. Spergel

In this paper we present an extension to the $\texttt{matryoshka}$ suite of neural-network-based emulators. The new editions have been developed to accelerate EFTofLSS analyses of galaxy power spectrum multipoles in redshift space. They are…

Cosmology and Nongalactic Astrophysics · Physics 2022-11-30 Jamie Donald-McCann , Kazuya Koyama , Florian Beutler

Modern cosmological surveys are delivering datasets characterized by unprecedented quality and statistical completeness; this trend is expected to continue into the future as new ground- and space-based surveys come online. In order to…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-21 Kelly R. Moran , Katrin Heitmann , Earl Lawrence , Salman Habib , Derek Bingham , Amol Upadhye , Juliana Kwan , David Higdon , Richard Payne

Testing gravity and the concordance model of cosmology, $\Lambda$CDM, at large scales is a key goal of this decade's largest galaxy surveys. Here we present a comparative study of dark matter power spectrum predictions from different…

We compare and validate COLA (COmoving Lagrangian Acceleration) simulations against existing emulators in the literature, namely Bacco and Euclid Emulator 2. Our analysis focuses on the non-linear response function, i.e., the ratio between…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-28 Guilherme Brando , Bartolomeo Fiorini , Kazuya Koyama , Hans A. Winther

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…

Training convolutional neural networks (CNNs) on high-resolution images is often bottlenecked by the cost of evaluating gradients of the loss on the finest spatial mesh. To address this, we propose Multiscale Gradient Estimation (MGE), a…

Machine Learning · Computer Science 2026-03-03 Shadab Ahamed , Niloufar Zakariaei , Eldad Haber , Moshe Eliasof

Upcoming galaxy surveys will bring a wealth of information about the clustering of matter, but modeling small-scale structure beyond $\Lambda$CDM remains computationally challenging. While accurate N-body emulators exist to model the matter…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-10 João Rebouças , Victoria Lloyd , Jonathan Gordon , Guilherme Brando , Vivian Miranda

Year 1 results of the Legacy Survey of Space and Time (LSST) will provide tighter constraints on small-scale cosmology, beyond the validity of linear perturbation theory. This heightens the demand for a computationally affordable…

Cosmology and Nongalactic Astrophysics · Physics 2024-08-27 Jonathan Gordon , Bernardo F. de Aguiar , João Rebouças , Guilherme Brando , Felipe Falciano , Vivian Miranda , Kazuya Koyama , Hans A. Winther

Micromagnetics has made significant strides, particularly due to its wide-ranging applications in magnetic storage design. Numerical simulation is a cornerstone of micromagnetics research, relying on first-principle rules to compute the…

Machine Learning · Computer Science 2024-10-22 Yunqi Cai , Jiangnan Li , Dong Wang

We test the convergence of fast simulations based on the COmoving Lagrangian Acceleration (COLA) method for predictions of the matter power spectrum, specialising our analysis in the redshift range $1 \le z \le 1.65$, relevant to…

Cosmology and Nongalactic Astrophysics · Physics 2023-11-21 Bartolomeo Fiorini , Kazuya Koyama , Tessa Baker