Rotational behaviors and magnetic field evolution of radio pulsars

Abstract

AbstractThe observed long‐term spin‐down evolution of isolated radio pulsars cannot be explained by the standard magnetic dipole radiation with a constant braking torque. However, how and why the torque varies remains still controversial, an outstanding problem in our understanding of neutron stars. We have constructed a phenomenological model of the evolution of surface magnetic fields of pulsars which contains a long‐term decay modulated by short‐term oscillations; a pulsar's spin is thus modified by its magnetic field evolution. The predictions of this model agree with the precisely measured spin evolution of several individual pulsars. The derived parameters suggest that the Hall drift and Hall waves in neutron star crusts are probably responsible for the long‐term change and short‐term quasi‐periodical oscillations, respectively. Many statistical properties of the timing noise of pulsars can well be reproduced with this model, including correlations and the distributions of the observed braking indices of the pulsars which span over a range of more than 100 millions. We have also presented a phenomenological model for the recovery processes of classical and slow glitches which can successfully model the observed slow and classical glitch events without biases. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)