Gravitation spin effect on the magnetic inclination evolution of pulsars

Abstract

If pulsar magnetic fields are associated with the intrinsic magnetic moment of neutrons inside the stellar crust, the gravitational spin effect can induce the magnetic axis to align with the rotation axis. Our theoretical results show that the decay time scale is inversely proportional to the magnetic field strength, and that longer initial period pulsars can delay the alignment process. Therefore the inclination angle of strong magnetic field pulsars should be distributed randomly but the weak field pulsars should concentrate towards lower values of inclination angle. Various statistical analyses comparing theoretical predictions and observational data have been done and satisfactory agreement between them obtained.