Lagrangian perturbation theory for a superfluid immersed in an elastic neutron star crust

TL;DR

This paper develops a Lagrangian perturbation theory framework to analyze the complex interactions between superfluid neutrons and elastic crust in neutron stars, crucial for understanding their dynamics and observable phenomena.

Contribution

It introduces a comprehensive theoretical approach incorporating superfluid entrainment, vortex pinning, mutual friction, and magnetic effects in neutron star crusts.

Findings

Framework for superfluid-elastic crust interactions

Insights into pulsar glitch mechanisms

Foundation for neutron star oscillation studies

Abstract

The inner crust of mature neutron stars, where an elastic lattice of neutron-rich nuclei coexists with a neutron superfluid, impacts on a range of astrophysical phenomena. The presence of the superfluid is key to our understanding of pulsar glitches, and is expected to affect the thermal conductivity and hence the evolution of the surface temperature. The coupling between crust and superfluid must also be accounted for in studies of neutron star dynamics, discussions of global oscillations and associated instabilities. In this paper we develop Lagrangian perturbation theory for this problem, paying attention to key issues like superfluid entrainment, potential vortex pinning, dissipative mutual friction and the star's magnetic field. We also discuss the nature of the core-crust interface. The results provide a theoretical foundation for a range of interesting astrophysical applications.