Radio Pulsar Spin-Down: Tests of Pulsar Models

Braking torques on radio pulsars are investigated for two classes of pulsar magnetosphere models, the so-called standard models with Goldreich-Julian current flow and models with much less current flow on open field lines and magnetic dipole braking. Spindown laws are obtained that include nutation effects due to a nonspherical solid crust. Analytic solutions for pulsar spindown are obtained for a number of cases. The pulsar P-P-dot distribution expected for a given spindown law and initial conditions is obtained by a Monte Carlo method and compared to the observed distribution. Acceptable fits are found for both standard models and magnetic dipole braking models. The form of the radio luminosity is critically important.