Spontaneous superfluid unpinning and the inhomogeneous distribution of vortex lines in neutron stars

The authors study the equation of motion of the pinned superfluid which couples to the crust of neutron stars via thermal vortex creep. An analytical solution can be obtained even when ωcr(r), the maximum value of the lag Ωs-Ωc that can be supported by pinning forces, has large spatial variations. Substantial inhomogeneous distributions of vortex lines will result from this kind of spatial variation. The authors suggest that such structural inhomogeneities in the crust of neutron stars may be responsible for frequent microglitches which lead to pulsar timing noise. Model calculations are compared with observations.