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Related papers: A Phase-Space Approach to Collisionless Stellar Sy…

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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

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

We present a new particle code for modelling the evolution of galaxies. The code is based on a multi-phase description for the interstellar medium (ISM). We included star formation (SF), stellar feedback by massive stars and planetary…

Astrophysics · Physics 2009-11-11 Stefan Harfst , Christian Theis , Gerhard Hensler

We present and discuss the development of an unconditionally stable algorithm used to solve the evolution equations of the Phase Field Crystal (PFC) model. This algorithm allows for an arbitrarily large algorithmic time step. As the basis…

Computational Physics · Physics 2009-11-13 Mowei Cheng , James A. Warren

We present the time-dependent complete-active-space self-consistent-field (TD-CASSCF) method to simulate multielectron dynamics in ultrafast intense laser fields from the first principles. While based on multiconfiguration expansion, it…

Atomic Physics · Physics 2018-04-24 Takeshi Sato , Yuki Orimo , Takuma Teramura , Oyunbileg Tugs , Kenichi L. Ishikawa

We propose a new semi-Lagrangian Vlasov-Poisson solver. It employs elements of metric to follow locally the flow and its deformation, allowing one to find quickly and accurately the initial phase-space position $Q(P)$ of any test particle…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-02 S. Colombi , C. Alard

This paper develops a two-stage stochastic model to investigate evolution of random fields on the unit sphere $\bS^2$ in $\R^3$. The model is defined by a time-fractional stochastic diffusion equation on $\bS^2$ governed by a diffusion…

Probability · Mathematics 2024-03-05 T. Alodat , Q. T. Le Gia , I. H. Sloan

The advent of datasets of stars in the Milky Way with six-dimensional phase-space information makes it possible to construct empirically the distribution function (DF). Here, we show that the accelerations can be uniquely determined from…

Astrophysics of Galaxies · Physics 2021-07-23 J. An , A. Naik , N. W. Evans , C. Burrage

Since the dawn of the space age, observations of energetic particles in planetary radiation belts have been interpreted within a diffusive transport framework, even though the processes that populate and deplete these belts produce highly…

Plasma Physics · Physics 2026-04-24 Adnane Osmane , Xin An , Anton Artemyev , Oliver Allanson , Jay Albert , Miroslav Hanzelka

We find a numerical self-consistent stellar model by finding the distribution function of a thin disk that satisfies simultaneously the Fokker-Planck and Poisson equations. The solution of the Fokker-Planck equation is found by a direct…

Astrophysics · Physics 2009-11-11 Maximiliano Ujevic , Patricio S. Letelier

The fundamental concept of phase space for particles moving in the four-dimensional spacetime is analyzed. Particle distribution density is defined as differential form, which degree may be different in various cases. It should be…

Classical Physics · Physics 2016-01-20 O. I. Drivotin

Simulation of plasmas in electromagnetic fields requires numerical solution of a kinetic equation that describes the time evolution of the particle distribution function. In this paper we propose a finite volume scheme based on integral…

Polymer self-consistent field theory techniques are used to derive quantum density functional theory without the use of the theorems of density functional theory. Instead, a free energy is obtained from a partition function that is…

Chemical Physics · Physics 2022-11-29 Russell B. Thompson

Placed slightly out of dynamical equilibrium, an isolated stellar system quickly returns towards a steady virialized state. We study this process of collisionless relaxation using the matrix method of linear response theory. We show that…

Astrophysics of Galaxies · Physics 2024-09-04 Simon Rozier , Raphaël Errani

We perform a numerical study of the critical regime for the general relativistic collapse of collisionless matter in spherical symmetry. The evolution of the matter is given by the Vlasov equation (or Boltzmann equation) and the geometry by…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Ignacio Olabarrieta

Self-consistent field theory (SCFT) is one of the useful methods to simulate phase separated structures of multi-component polymer systems. In this article, we propose an SCFT for semiflexible polymer melts, where the basic equations for…

Soft Condensed Matter · Physics 2025-03-04 Yutaka Oya , Toshihiro Kawakatsu

We present an approach for simulating the collisional evolution of spherical isotropic stellar systems based on the one-dimensional Fokker-Planck equation. A novel aspect is that we use the phase volume as the argument of the distribution…

Astrophysics of Galaxies · Physics 2017-10-06 Eugene Vasiliev

In the stochastic mean-field (SMF) approach, an ensemble of initial values for a selected set of one-body observables is formed by stochastic sampling from a phase-space distribution that reproduces the initial quantum fluctuations.…

Nuclear Theory · Physics 2015-06-22 Bulent Yilmaz , Denis Lacroix , Resul Curebal

We consider a perturbative approach to the Vlasov-Poisson system for cosmic structure formation that does not rely on any truncation of the momentum-cumulant hierarchy. The generally non-trivial linear solution is computed by solving a…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-14 Hannes Heisler , Marvin Sipp , Matthias Bartelmann

Particle acceleration in collisionless plasma systems is a central question in astroplasma and astroparticle physics. The structure of the acceleration regions, electron-ion energy equilibration, preacceleration of particles at shocks to…

High Energy Astrophysical Phenomena · Physics 2020-02-19 Martin Pohl , Masahiro Hoshino , Jacek Niemiec