Bulk viscosity of superfluid neutron stars

Abstract

The hydrodynamics describing dynamical effects in superfluid neutron stars essentially differs from the standard one-fluid hydrodynamics. In particular, we have four bulk viscosity coefficients in the theory instead of one. In this paper we calculate these coefficients, for the first time, assuming they are due to nonequilibrium beta processes (such as modified or direct Urca process). The results of our analysis are used to estimate characteristic damping times of sound waves in superfluid neutron stars. It is demonstrated that all four bulk viscosity coefficients lead to comparable dissipation of sound waves and should be considered on the same footing.

Identifiers

DOI

10.1103/physrevd.76.083001

Citations and references