Superfluid Core Rotation in Pulsars. II. Postjump Relaxations

Abstract

A theory of nonstationary dynamics of neutron star superfluid core rotation, based on the dynamics of proton vortex clusters is presented. Exact solutions describing the postjump relaxation of the superfluid component of the star are given with allowance for the spatial dependence of viscous friction. In this theory, the core is coupled on timescales of hours to years, rather than the few seconds' coupling time in models where vortex clusters are ignored. An application of the theory to the postjump relaxations of the Vela pulsar 0833-45 shows that, within the standard range of parameters of neutron stars, the postjump relaxations of Vela can be understood in terms of the dynamics of the superfluid core. The model involves contributions to postjump relaxations from a wide range of radii, with relaxation times scaling as the square of the spin period. It is predicted that millisecond pulsars will not show timing irregularities on timescales larger than a few days.