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

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The interiors of mature neutron stars are expected to be superfluid. Superfluidity of matter on the microscopic scale can have a number of large scale, potentially observable consequences, as the superfluid component of the star can now…

High Energy Astrophysical Phenomena · Physics 2019-12-11 Vadym Khomenko , Marco Antonelli , Brynmor Haskell

We discuss bulk viscosity due to non-leptonic processes involving hyperons and Bose-Einstein condensate of negatively charged kaons in neutron stars. It is noted that the hyperon bulk viscosity coefficient is a few order of magnitude larger…

Astrophysics · Physics 2008-12-31 Debarati Chatterjee , Debades Bandyopadhyay

We develop a general formalism to treat, in general relativity, the linear oscillations of a two-fluid star about static (non-rotating) configurations. Such a formalism is intended for neutron stars, whose matter content can be described,…

General Relativity and Quantum Cosmology · Physics 2009-10-31 G. L. Comer , David Langlois , Lap Ming Lin

We consider the hydrodynamics of the outer core of a neutron star under conditions when both neutrons and protons are superfluid. Starting from the equation of motion for the phases of the wave functions of the condensates of neutron pairs…

Quantum Gases · Physics 2017-03-02 D. N. Kobyakov , C. J. Pethick

We examine the cosmological consequences of an alternative to the standard expression for bulk viscosity, one which was proposed to avoid the propagation of superluminal signals without the necessity of extending the space of variables of…

General Relativity and Quantum Cosmology · Physics 2016-04-08 Marcelo M. Disconzi , Thomas W. Kephart , Robert J. Scherrer

We construct a relativistic model for bulk viscosity and heat conduction in a superfluid. Building on the principles of Unified Extended Irreversible Thermodynamics, the model is derived from Carter's multifluid approach for a theory with 3…

General Relativity and Quantum Cosmology · Physics 2022-02-23 Lorenzo Gavassino , Marco Antonelli , Brynmor Haskell

As a follow up to articles dealing firstly with a convective variational formulation in a Milne-Cartan framework for non-dissipative multi fluid models, and secondly with various ensuing stress energy conservation laws and generalised…

Astrophysics · Physics 2009-11-10 Brandon Carter , Nicolas Chamel

A weakly magnetized neutron star (NS) undergoing disk accretion should release about a half of its power in a compact region known as the accretion boundary layer. Latitudinal spread of the accreted matter and efficient radiative cooling…

High Energy Astrophysical Phenomena · Physics 2025-05-08 Aleksandr Rusakov , Pavel Abolmasov , Omer Bromberg

We investigate the structural, dynamical, and oscillatory properties of neutron stars admixed with dark matter, modeled via a single-fluid formalism where dark matter interacts with nuclear matter through an effective Higgs-portal coupling.…

High Energy Astrophysical Phenomena · Physics 2025-06-03 Ankit Kumar , Hajime Sotani

Spherically symmetric simulations of stellar core collapse and post-bounce evolution are used to test the sensitivity of the supernova dynamics to different variations of the input physics. We consider a state-of-the-art description of the…

Astrophysics · Physics 2007-05-23 M. Rampp , R. Buras , H. -Th. Janka , G. Raffelt

In this paper, we discuss the damping of density oscillations in dense nuclear matter in the temperature range relevant to neutron star mergers. This damping is due to bulk viscosity arising from the weak interaction ``Urca'' processes of…

Nuclear Theory · Physics 2020-06-23 Mark Alford , Arus Harutyunyan , Armen Sedrakian

We propose a bulk viscous unified dark matter scenario based on a nonlinear extension of the full causal Israel-Stewart theory. This framework allows the viscous fluid to remain far from equilibrium, an essential feature for a physically…

General Relativity and Quantum Cosmology · Physics 2025-12-16 Guillermo Palma , Gabriel Gomez

We have developed a theoretical model and a numerical code for stationary rotating superfluid neutron stars in full general relativity. The underlying two-fluid model is based on Carter's covariant multi-fluid hydrodynamic formalism. The…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Reinhard Prix , Jerome Novak , G. L. Comer

We present a scattering amplitude formalism to study the tidal heating effects of nonspinning neutron stars incorporating both worldline effective field theory and relativistic stellar perturbation theory. In neutron stars, tidal heating…

General Relativity and Quantum Cosmology · Physics 2024-12-09 M. V. S. Saketh , Zihan Zhou , Suprovo Ghosh , Jan Steinhoff , Debarati Chatterjee

We perform fully general-relativistic simulations of binary strange star mergers considering two different approaches for thermal effects. The first uses a cold equation of state (EOS) derived from a modified version of the MIT bag model…

High Energy Astrophysical Phenomena · Physics 2025-04-08 Francesco Grippa , Aviral Prakash , Domenico Logoteta , David Radice , Ignazio Bombaci

In order to establish whether the unstable r-modes in a rotating neutron star provide a detectable source of gravitational waves, we need to understand the details of the many dissipative processes that tend to counteract the instability.…

Solar and Stellar Astrophysics · Physics 2015-05-18 Brynmor Haskell , Nils Andersson

Long-term neutrino-radiation resistive-magnetohydrodynamics simulations in full general relativity are performed for a system composed of a massive neutron star and a torus formed as a remnant of binary neutron star mergers. The simulation…

High Energy Astrophysical Phenomena · Physics 2021-09-21 Masaru Shibata , Sho Fujibayashi , Yuichiro Sekiguchi

We consider a rotating neutron star with the presence of hyperons in its core, using an equation of state in an effective chiral model within the relativistic mean field approximation. We calculate the hyperonic bulk viscosity coefficient…

High Energy Physics - Phenomenology · Physics 2014-11-20 T. K. Jha , H. Mishra , V. Sreekanth

We study time evolutions of superfluid neutron stars, focussing on the nature of the oscillation spectrum, the effect of mutual friction force on the oscillations and the hydrodynamical spin-up phase of pulsar glitches. We linearise the…

Solar and Stellar Astrophysics · Physics 2015-05-18 A. Passamonti , N. Andersson

The Bethe-Brueckner-Goldstone many-body theory of the Nuclear Equation of State is reviewed in some details. In the theory, one performs an expansion in terms of the Brueckner two-body scattering matrix and an ordering of the corresponding…

Nuclear Theory · Physics 2007-05-23 Marcello Baldo , Fiorella Burgio