Newtonian mechanics of neutron superfluid in elastic star crust

Abstract

To account for pulsar frequency glitches, it is necessary to use a neutron star crust model allowing not only for neutron superfluidity but also for elastic solidity. These features have been treated separarately in previous treatments of crust matter, but are combined here in a unified treatment that is based on the use of a Lagrangian master functon, so that the coherence the system is ensured by the relevant Noether identities. As well as the model obtained directly from the variation principle, the same master function can provide other conservative alternatives, allowing in particular for the effect of perfect vortex pinning. It is also shown how such models can be generalised to allow for dissipative effects, including that of imperfect pinning, meaning vortex drag or creep.