Are pulsars born as slow rotators?

The authors have modeled the observed properties of pulsars on the assumption that they evolve by emitting magnetic dipole radiation and have exponentially decaying magnetic fields. The observed properties are affected by the dependence of radio luminosity (L) on period (P) and period derivative (P). If one adopts the recently determined relation L ∝ P-1P1/3, then the observed period distribution is well fitted by a model which assumes flat initial distributions with initial periods ranging from 0.09 to 0.25 s. The authors have also estimated the distribution of pulsar z-velocities from observations and used it with their model to calculate the variation of pulsar number, period, and characteristic age with height z.