Shear viscosity and the r-mode instability window in superfluid neutron stars

Abstract

We analyze how recent computations of the shear viscosity $\eta$ in the core of superfluid neutron stars affect the r-mode instability window. We first analyze the contribution of superfluid phonons to the viscosity, both in their hydrodynamical and ballistic regime. We also consider the recent computation of $\eta$ arising from the collisions of electrons with electrons and protons by Shternin and Yakovlev, and discuss how the interactions among superfluid phonons and electrons might contribute to the shear viscosity. For assessing the r-mode instability window we compare the shear viscosity due to phonons in the hydrodynamical regime with respect to the shear viscosity due to electron collisions. Only at high temperatures the superfluid phonon contribution to $\eta$ starts to dominate the process of r-mode damping. While our results for the instability window are preliminary, as other dissipative processes should be taken into account as well, they differ from previous evaluations of the r-mode damping due to the shear viscosity in superfluid neutron stars.

16 pages, 5 figures, version to be published in Physical Review D

References in corpus (14)

• Color superconductivity in dense quark matter
• Neutron Star Observations: Prognosis for Equation of State Constraints
• General coordinate invariance and conformal invariance in nonrelativistic physics: Unitary Fermi gas
• Shear viscosity in neutron star cores
• Spin Evolution of Accreting Neutron Stars: Nonlinear Development of the R-mode Instability
• Shear viscosity of a superfluid Fermi gas in the unitarity limit
• Ekman layer damping of r-modes revisited
• Chiral Fermi liquid approach to neutron matter
• Mutual friction in a cold color flavor locked superfluid and r-mode instabilities in compact stars
• Collective modes of the order parameter in a triplet superfluid neutron liquid
• Zero sound in triplet-correlated superfluid neutron matter
• Weak response of neutron matter at low momentum transfer
• Phonon contribution to the shear viscosity of a superfluid Fermi gas in the unitarity limit
• Bulk viscosity coefficients due to phonons in superfluid neutron stars

Cited by in corpus (8)

• On the importance of viscous dissipation and heat conduction in binary neutron-star mergers
• R-modes in neutron stars: Theory and observations
• Viscosity of neutron star matter and $r$-modes in rotating pulsars
• Thermal conductivity due to phonons in the core of superfluid neutron stars
• The shear viscosity of two-flavor crystalline color superconducting quark matter
• Bulk viscosity coefficients due to phonons in superfluid neutron stars
• Transport properties of superfluid phonons in neutron stars
• Gauge-invariant perturbations of relativistic non-perfect fluids in spherical spacetime