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Article Dans Une Revue Physical Review D Année : 2023

Simulating bulk viscosity in neutron stars I: formalism

Giovanni Camelio
  • Fonction : Auteur
Lorenzo Gavassino
  • Fonction : Auteur
Sebastiano Bernuzzi
  • Fonction : Auteur
Brynmor Haskell
  • Fonction : Auteur

Résumé

The faithful inclusion of the effects of bulk viscosity induced by the presence of chemical reactions is an important issue for simulations of core-collapse supernovae, binary neutron star mergers and neutron star oscillations, where particle abundances are locally pushed out of chemical equilibrium by rarefaction and compression of the fluid elements. In this work, we discuss three different approaches that can be used to implement bulk viscosity in general relativistic hydrodynamic simulations of neutron stars: the exact multi-component reacting fluid, and two Müller-Israel-Stewart theories, namely the second order Hiscock-Lindblom model and its linear limit, the Maxwell-Cattaneo model. After discussing the theory behind the three approaches, we specialize their dynamics equations to spherical symmetry in the radial gauge-polar slicing (i.e., Schwarzschild) coordinates. We also discuss a particular choice for the equation of state of the fluid and the associated neutrino emission rates, which are used in a companion paper for the numerical comparison of the three frameworks, and we obtain the effective sound speed for the Hiscock-Lindblom theory in the non-linear regime.

Dates et versions

hal-03662769 , version 1 (09-05-2022)

Identifiants

Citer

Giovanni Camelio, Lorenzo Gavassino, Marco Antonelli, Sebastiano Bernuzzi, Brynmor Haskell. Simulating bulk viscosity in neutron stars I: formalism. Physical Review D, 2023, 107 (10), pp.103031. ⟨10.1103/PhysRevD.107.103031⟩. ⟨hal-03662769⟩
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