A novel mechanism for the decay of neutron star magnetic fields

Abstract

If the generally accepted picture that the neutrons and protons in the core of a neutron star will be in a (vortex) superfluid state is correct, then the Onsager-Feynman vortices in the neutron superfluid and the Abrikosov vortices in the proton superfluid may be strongly interpinned. We argue that because of this the evolution of the magnetic field will be intimately related to the rotational history of the star. Based on this hypothesis we present a model for the decay of the magnetic fields of neutron stars. We point out that our model is able to explain for the first time, at least qualitatively, many of the outstanding questions such as (i) the exponential decay of the field in young pulsars, (ii) preponderance of binaries among low- field pulsars, (iii) why very old (>10⁹yr) neutron stars retain substantial residual fields and what determines this residual value, etc.