Diffusion as a damping mechanism for neutron-star oscillations

Abstract

We study the effects of diffusion on damping of oscillations in the neutron star cores. This dissipation mechanism is usually ignored in the literature. As we show, the effect of diffusion is always smaller than viscous dissipation if the normal (nonsuperfluid and nonsuperconducting) matter of neutron stars is considered. However, we argue that for superconducting stars the role of diffusion may increase.

Dissipative relativistic magnetohydrodynamics of a multicomponent mixture and its application to neutron stars

“…First of all, one can employ the dissipative MHD for studying magnetothermal evolution in the internal layers of NSs, accounting for diffusion, macroscopic flows, and the effects of general relativity; the corresponding equations for a spherically symmetric NS with npeµ core composition were explicitly written out in Sec. V. Diffusion may also play an important role in damping of NS oscillations [84], although this effect has not been studied previously, to the best of our knowledge. As for the development of hydrodynamic theory, the next logical step would be to generalize the dissipative MHD to the superfluid and superconducting mixtures [51], i.e., combine the results of the present paper with the nondissipative superfluid MHD of Ref.…”

Dissipative superfluid relativistic magnetohydrodynamics of a multicomponent fluid: the combined effect of particle diffusion and vortices

“…All these works ignore particle diffusion, i.e., relative motions of different particle species (or Bogoliubov thermal excitations, if superfluid/superconducting species are considered) with respect to each other. This is an unfortunate omission, since it is well-known that diffusion plays a crucial role in the secular evolution of the magnetic field in nonsuperfluid and nonsuperconducting NSs [32][33][34][35][36][37][38] and, moreover, can be very efficient [39,40] in damping of NS oscillations and suppressing various instabilities in their interiors. As shown recently [41], diffusion also has a major effect on the evolution of the magnetic field in superconducting NSs.…”