Generation of Pulsar Glitches: a Superfluid Core Model A

We show that the neutron star's crust-core interface acts as a potential barrier on the peripheral neutron vortices approaching this interface and thus prevents their continuous decay on it in the course of equilibrium state deceleration. The barrier arises due to the interaction of vortex magnetic flux with the Meissner currents set up by the crustal magnetic field at the interface. When the non-balanced part of the Magnus force reaches the value at which the vortices are able to annihilate at the interface, the rapid transfer of angular momentum from the superfluid spins-up the observable crust on short dynamical coupling times. Models of generation of pulsar glitches are supposed to explain the following observational facts: (i) the short spin-up time scales, which are less than 120 s in the Vela pulsar 0833–45 and less than an hour in the Crab pul-sar 0531+21; (ii) the magnitudes of the jumps in the rotation and spin down rates, ∆ν/ν ∼ 10 −8 −10 −6 and ∆ ˙ ν/ ˙ ν ∼ 10 −3 −10 −2 , respectively; and (iii) the origin of the instability driving a glitch along with characteristic intervals between glitches (typically of the order of several months to years). A number of existing generic models invoke as trigger crust-and core-quakes 1 (discontinu-ous adjustments of the solid crust to the gradually changing oblateness of the star as it spins down); spontaneous quantum transitions of rotating superfluid between quasistationary eigenstates corresponding to different eigenvalues of total angular momentum 2 ; collective unpinning of a large number (∼ 10 13) of vortices in the neutron star crusts 3,4 and thermal instabilities 5. The increasing bulk of observational evidence provides good chances of discrimination between the theoretical models in the future. Here we shall give a brief account of a new trigger mechanism for generation of pulsar glitches in neutron star's superfluid core. The complete discussion will be given in ref. 6. In the interjump epoch a neutron star is decelerating; consequently the vortex lattice in the superfluid core is expanding and the peripheral vortices attempt to cross the crust-core boundary. The crust-superfluid core interface acts as a potential barrier on the vortices in the superfluid core that approach this boundary. The barrier arises due to the magnetic interaction between the crustal magnetic field H 0 (which penetrates the superconducting