Vortex-interface interactions and generation of glitches in pulsars

Abstract

We show that the crust-core interface in neutron stars acts as a potential barrier to the peripheral neutron vortices approaching the interface in the model in which these are coupled to the proton vortex clusters. This elementary barrier because of the interaction of vortex magnetic flux with the Meissner currents set up by the crustal magnetic field at the interface. The dominant part of the force is derived from to the cluster-interface interaction. As a result of the stopping of the continuous neutron vortex current through the interface, angular momentum is stored in the superfluid layers in the vicinity of the crust-core interface during the interglitch period. Discontinuous annihilation of proton vortices on the boundary restores the neutron vortex current and spins up the observable crust on short time-scales, leading to a glitch in the spin characteristics of a pulsar.Comment: 12 pages, 3 figures. Final version to appear in MNRAS; includes a new discussion of the problem in the spherical geometry; some rewording; references revise

Relativistic Superfluid Models for Rotating Neutron Stars

“…A less clear cut case example is that of the Crab, for which the observed value [48], namely 1/2, is also positive but considerably smaller, which suggests that this may be another instance to which Ruderman model applies, though with a relatively high misalignment angle. However in view of the above mentionned likelihood [46,47] of other of other positive contributions to , this evidence is too inconclusive to exclude the possibility that the Crab glitches may, after all, be attributable a slippage mechanism [35,36,37] of the first category, or even to the original simple oblateness mechanism subject to (21).…”

“…Another reason for an increase of the spin down rate would be the decrease in oblateness according to (18), but this would evidently be much less important. Unlike the original single constituent mechanism [22,8,23,7] based on the loss of moment of inertia due to decrease in oblateness, and unlike the versions [35,36,37] of the twoconstituent theory that attribute the glitches to discontinuous vortex slippage, but like the Ruderman version [38,39] (that applies when the pinning is too strong to be broken) the newly proposed two-constituent mechanism [40] (that applies when the pinning is too weak to be effective) will also entail a substantial rate of long term drift of plates of crust material. 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000 However this centrifugal buoyancy deficit mechanism differs from Ruderman's pinning driven mechanism in a manner that may be experimentally observable, since it is expected to produce plate drift in just the opposite direction, meaning that of decreasing colatitude θ for an isolated spinning down pulsar (see Figure 3), entailing transfusion of matter into the crust constituent near the equator, and out of it nearer the poles where θ is small.…”

“…Like their more recent variants, the various early versions were classifiable in two distinct categories. In the first category [24,35] it was supposed that the discontinuous breakdown would occur when some maximum static pinning force value was exceeded: the sudden (rather than "creeping") nature of the breakdown was accounted for, in a recent version [36], as being due to a thermal instability resulting from the temperature sensitivity of c r , while another new suggestion [37] is that the relevant slippage occurs at the locus where the ions dissolve at the base of the crust. In the second category [24,38,39] it was suggested that such a maximum pinning force value might never be reached because the elastic solid structure would breakdown first in a crustquake (of the kind required in the single constituent moment of inertia changing mechanism that may account for cases such as that of the Crab).…”

Crustal Entrainment and Pulsar Glitches

“…2 and the fact that G < ∼ 2% suggest the existence of a reservoir of angular momentum in a limited region of the star, possibly in the outermost part of the core just below the crust (e.g., Refs. [47,48]). This warrants further studies.…”

Propagation of the ultrashort pulsed beam with ultrabroad bandwidth in the dispersive medium

“…This sudden decrease in the angular momentum of the superfluid within the crust results in a sudden increase in angular momentum of the rigid crust itself, and hence a glitch. Perhaps, due to interactions between neutron vortices and proton flux tubes, the neutron vortices pile up just inside the inner crust before suddenly coming unpinned [125]. Although the models differ in important respects, all agree that the fundamental requirements are the presence of rotational vortices in a superfluid, and the presence of a rigid structure which impedes the motion of these vortices (by a pinning force of suitable magnitude) and which encompasses enough of the volume of the pulsar to contribute significantly to the total moment of inertia.…”