Pinning and Binding Energies for Vortices in Neutron Stars: Comments on Recent Results

Understand

We investigate when the energy that pins a superfluid vortex to the lattice of nuclei in the inner crust of neutron stars can be approximated by the energy that binds the vortex to a single nucleus.

• Indeed, although the pinning energy is the quantity relevant to the theory of pulsar glitches, so far full quantum calculations have been possible only for the binding energy.
• Physically, the presence of nearby nuclei can be neglected if the lattice is dilute, namely with nuclei sufficiently distant from each other.
• We find that the dilute limit is reached only for quite large Wigner-Seitz cells, with radii > 55 fm; these are found only in the outermost low-density regions of the inner crust.