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Related papers: The Cosmic Linear Anisotropy Solving System (CLASS…

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Homogeneous and nearly-isotropic cosmological models are natural extensions of standard Friedmann cosmologies. Constraining their features is crucial, as any detection of their properties would impact our understanding of inflation and the…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-16 João G. Vicente , Thiago S. Pereira , Cyril Pitrou

We describe some scaling issues that arise when using lattice Boltzmann methods to simulate binary fluid mixtures -- both in the presence and in the absence of colloidal particles. Two types of scaling problem arise: physical and…

Soft Condensed Matter · Physics 2009-11-10 M. E. Cates , J. -C. Desplat , P. Stansell , A. J. Wagner , K. Stratford , R. Adhikari , I. Pagonabarraga

The majority of present efforts to constrain cosmological parameters with cosmic microwave background (CMB) anisotropy data employ approximate likelihood functions, the time consuming nature of a complete analysis being a major obstacle. We…

Astrophysics · Physics 2007-05-23 M. Douspis , J. G. Bartlett , A. Blanchard , M. Le Dour

This paper presents a systematic and accurate treatment of the evolution of cosmological perturbations in self-interacting dark matter models, for particles which decoupled from the primordial plasma while relativistic. We provide a…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-17 Rafael Yunis , Carlos R. Argüelles , Claudia G. Scóccola , Diana López Nacir , Gastón Giordano

We develop a highly accurate analytic approximation for small-scale non-cold relic perturbations by solving the collisionless Boltzmann equation in the quasi-stationary regime. The approximation is implemented in CLASSIER (CLASS Integral…

Cosmology and Nongalactic Astrophysics · Physics 2025-11-20 Nanoom Lee , Yacine Ali-Haïmoud , Marc Kamionkowski

In this paper, we investigate the numerous parameters choices for linear lattice Boltzmann schemes according to the definition of the isotropic order given in \cite{ADG11}. This property---written in a general framework including all of the…

Analysis of PDEs · Mathematics 2011-12-13 Adeline Augier , François Dubois , Benjamin Graille

Complex colloidal fluids, such as emulsions stabilized by complex shaped particles, play an important role in many industrial applications. However, understanding their physics requires a study at sufficiently large length scales while…

Soft Condensed Matter · Physics 2012-04-27 Florian Günther , Florian Janoschek , Stefan Frijters , Jens Harting

We propose a novel numerical method for solving multi-dimensional, special relativistic Boltzmann equations for neutrinos coupled to hydrodynamics equations. It is meant to be applied to simulations of core-collapse supernovae. We handle…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Hiroki Nagakura , Kohsuke Sumiyoshi , Shoichi Yamada

We propose a new second-order accurate lattice Boltzmann scheme that solves the quasi-static equations of linear elasticity in two dimensions. In contrast to previous works, our formulation solves for a single distribution function with a…

Numerical Analysis · Mathematics 2022-12-14 Oliver Boolakee , Martin Geier , Laura De Lorenzis

We present a simple, yet accurate approximation for calculating the cosmic microwave background anisotropy power spectrum in adiabatic models. It consists of solving for the evolution of a two-fluid model until the epoch of recombination…

Astrophysics · Physics 2009-10-22 Uros Seljak

We present a numerically efficient and accurate implementation of the Passaglia-Hu effective fluid approximation for ultralight axions (ULAs) within the Boltzmann code CAMB. This method is specifically designed to evolve the axion field…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-24 Adam Moss , Lauren Gaughan , Anne M. Green

A cosmological hydrodynamic code is described, which includes a routine to compute cosmic ray acceleration and transport in a simplified way. The routine was designed to follow explicitly diffusive acceleration at shocks, and second-order…

Astrophysics · Physics 2007-05-23 Dongsu Ryu , Francesco Miniati , Tom W. Jones , Hyesung Kang

The scalar mode temperature fluctuations of the cosmic microwave background has been derived in a spatially closed universe from two different methods. First, by following the photon trajectory after the last scattering and then from the…

General Relativity and Quantum Cosmology · Physics 2017-09-27 Pedram Niazy , Amir H. Abbassi

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

We present some accurate and efficient computations of large scale structure observables, obtained with a modified version of the CLASS code which is made publicly available. This code includes all relativistic corrections and computes both…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-04 Enea Di Dio , Francesco Montanari , Julien Lesgourgues , Ruth Durrer

It has been demonstrated that Lattice Boltzmann schemes (LBSs) are very efficient for Computational AeroAcoustics (CAA). In order to handle the issue of absorbing acoustic boundary conditions for LBS, three kinds of damping terms are…

Computational Physics · Physics 2012-03-30 Hui Xu , Pierre Sagaut

We study the gravitational lensing effect on the Cosmic Microwave Background (CMB) anisotropies performing a ray-tracing of the primordial CMB photons through intervening large-scale structures (LSS) distribution predicted by N-Body…

Cosmology and Nongalactic Astrophysics · Physics 2015-04-09 Matteo Calabrese , Carmelita Carbone , Giulio Fabbian , Marco Baldi , Carlo Baccigalupi

We develop the transport operator formalism, a new line-of-sight integration framework to calculate the anisotropies of the Cosmic Microwave Background (CMB) at the linear and non-linear level. This formalism utilises a transformation…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-25 Christian Fidler , Kazuya Koyama , Guido W. Pettinari

The Cosmology Large Angular Scale Surveyor (CLASS) is an experiment to measure the signature of a gravita-tional-wave background from inflation in the polarization of the cosmic microwave background (CMB). CLASS is a multi-frequency array…

We introduce a statistical measure of the effective model complexity, called the Bayesian complexity. We demonstrate that the Bayesian complexity can be used to assess how many effective parameters a set of data can support and that it is a…

Astrophysics · Physics 2007-07-23 Martin Kunz , Roberto Trotta , David Parkinson