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Related papers: Simulating bulk viscosity in neutron stars. I. For…

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We review the numerical techniques for ideal and non-ideal magneto-hydrodynamics (MHD) used in the context of star formation simulations. We outline the specific challenges offered by modeling star forming environments, which are dominated…

Instrumentation and Methods for Astrophysics · Physics 2019-07-22 Romain Teyssier , Benoit Commercon

Three-dimensional hydrodynamical simulations are presented for the direct head-on or off-center collision of two neutron stars, employing a basically Newtonian PPM code but including the emission of gravitational waves and their…

Astrophysics · Physics 2007-05-23 Maximilian Ruffert , H. -Thomas Janka

Exact values for bulk and shear viscosity are important to characterize a fluid and they are a necessary input for a continuum description. Here we present two novel methods to compute bulk viscosities by non-equilibrium molecular dynamics…

Soft Condensed Matter · Physics 2016-06-22 Gerhard Jung , Friederike Schmid

We perform binary neutron star merger simulations using a newly derived set of finite-temperature equations of state in the Brueckner-Hartree-Fock approach. We point out the important and opposite roles of finite temperature and rotation…

General Relativity and Quantum Cosmology · Physics 2021-04-21 A. Figura , F. Li , J. -J. Lu , G. F. Burgio , Z. H. Li , H. -J. Schulze

We study the evolution of a flat Friedmann-Robertson-Walker Universe, filled with a bulk viscous cosmological fluid, in the presence of time varying ``constants''. The dimensional analysis of the model suggests a proportionality between the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 José Antonio Belinchón , Indrajit Chakrabarty

The dependence of the bulk viscosity with the relativistic parameter $z=kT/mc^{2}$, obtained through the complete Boltzmann equation [1,2], is thoroughly analyzed. A complete and rigorous examination of the relevant non-relativistic and…

Statistical Mechanics · Physics 2019-10-02 A. L. Garcia-Perciante , L. Franco-Perez , A. R. Mendez

We investigate the realization of non-singular bouncing cosmologies driven by causal bulk-viscous fluids within General Relativity, $f(R)$ gravity, and Loop Quantum Cosmology. Building on the no-go result of Eckart theory in spatially flat…

General Relativity and Quantum Cosmology · Physics 2026-02-05 L. Yildiz , D. Kayki , E. Gudekli

We discuss slowly-rotating, general relativistic, superfluid neutron stars in the Hartle-Thorne formulation. The composition of the stars is described by a simple two-fluid model which accounts for superfluid neutrons and all other…

General Relativity and Quantum Cosmology · Physics 2023-03-21 Eneko Aranguren , José A. Font , Nicolas Sanchis-Gual , Raül Vera

We review recent advances in the numerical modeling of turbulent flows and star formation. An overview of the most widely used simulation codes and their core capabilities is provided. We then examine methods for achieving the…

Astrophysics of Galaxies · Physics 2026-04-22 Christoph Federrath , Stella Offner

We investigate the problem of periodically modulated strongly interacting neutron matter. We carry out ab initio non-perturbative auxiliary-field diffusion Monte Carlo calculations using an external sinusoidal potential in addition to…

Nuclear Theory · Physics 2017-04-11 Mateusz Buraczynski , Alexandros Gezerlis

Evolution of the bulk viscous matter dominated universe has been analysed using the full causal, Israel-Stewart theory for the evolution of bulk viscous pressure in the context of recent acceleration of the universe. The form of bulk…

General Relativity and Quantum Cosmology · Physics 2018-04-23 Jerin Mohan N D , Athira Sasidharan , Titus K Mathew

We develop a new framework for the modelling of charged fluid dynamics in general relativity. The model, which builds on a recently developed variational multi-fluid model for dissipative fluids, accounts for relevant effects like the…

General Relativity and Quantum Cosmology · Physics 2017-05-31 N. Andersson , K. Dionysopoulou , I. Hawke , G. L. Comer

The radial oscillations of neutron stars are studied using equations of state derived from density-dependent relativistic mean-field (DDRMF) models, which effectively describe the ground-state properties of finite nuclei. A novel numerical…

Nuclear Theory · Physics 2025-08-19 Xuesong Geng , Kaixuan Huang , Hong Shen , Lei Li , Jinniu Hu

We consider a first order formulation of relativistic fluids with bulk viscosity based on a stress-energy tensor introduced by Lichnerowicz. Choosing a barotropic equation of state, we show that this theory satisfies basic physical…

General Relativity and Quantum Cosmology · Physics 2017-10-25 Marcelo M. Disconzi , Thomas W. Kephart , Robert J. Scherrer

We present the first numerical simulations of the symmetric--hyperbolic theory for conformal dissipative relativistic fluids developed in [1]. In this theory, the information of the fluid dynamics is encoded in a scalar generating function…

General Relativity and Quantum Cosmology · Physics 2023-05-26 Pablo Montes , Marcelo E. Rubio , Oscar A. Reula

We derive the hydrodynamical equations of r-mode oscillations in neutron stars in presence of a novel damping mechanism related to particle number changing processes. The change in the number densities of the various species leads to new…

High Energy Physics - Phenomenology · Physics 2013-04-30 Giuseppe Colucci , Massimo Mannarelli , Cristina Manuel

The flow inside remnants of binary neutron star (NS) mergers is expected to be turbulent, because of magnetohydrodynamics instability activated at scales too small to be resolved in simulations. To study the large-scale impact of these…

High Energy Astrophysical Phenomena · Physics 2017-03-20 David Radice

Nonlinear simulations of neutron star mergers are complicated by the need to represent turbulent dynamics. As we cannot (yet) perform simulations that resolve accurately both the gravitational-wave scale and the smallest scales at which…

High Energy Astrophysical Phenomena · Physics 2025-01-07 Thomas Celora , Nils Andersson , Ian Hawke , Greg L. Comer , Marcus J. Hatton

Results of 3D, Newtonian hydrodynamic calculations of the last stages of the inspiral and the final coalescence of neutron star binary systems are described. The focus is on sligthly asymmetric systems with the asymmetry stemming either…

Astrophysics · Physics 2008-11-26 S. Rosswog , M. B. Davies , F. -K. Thielemann , T. Piran

Feedback from massive stars is one of the least understood aspects of galaxy formation. We perform a suite of vertically stratified local interstellar medium (ISM) simulations in which supernova rates and vertical gas column densities are…

Astrophysics · Physics 2009-09-24 M. Ryan Joung , Mordecai-Mark Mac Low , Greg L. Bryan