Damping of sound waves in superfluid nucleon-hyperon matter of neutron stars

TL;DR

This paper investigates how sound waves propagate and damp in superfluid nucleon-hyperon matter within neutron star cores, highlighting significant differences in damping times when accounting for superfluid effects.

Contribution

It applies a recent dissipative relativistic hydrodynamics framework to analyze sound wave damping in superfluid neutron star matter, revealing large discrepancies from non-superfluid models.

Findings

Damping times can differ by several orders of magnitude between superfluid and normal models.

Sound speeds and damping times depend on shear viscosity and weak interaction processes.

Superfluid effects significantly influence wave propagation in neutron star cores.

Abstract

We consider sound waves in superfluid nucleon-hyperon matter of massive neutron-star cores. We calculate and analyze the speeds of sound modes and their damping times due to the shear viscosity and non-equilibrium weak processes of particle transformations. For that, we employ the dissipative relativistic hydrodynamics of a superfluid nucleon-hyperon mixture, formulated recently [M.E. Gusakov and E.M. Kantor, Phys. Rev. D78, 083006 (2008)]. We demonstrate that the damping times of sound modes calculated using this hydrodynamics and the ordinary (nonsuperfluid) one, can differ from each other by several orders of magnitude.