Disk-assisted Spin-down of Young Radio Pulsars

Abstract

We present a model for the spindown of young radio pulsars in which theneutron star loses rotational energy not only by emitting magnetic dipoleradiation but also by torquing a surrounding accretion disk produced bysupernova fallback. The braking index predicted in our model is in general lessthan n=3 (the value for pure dipole magnetic radiation), in agreement with thereported values of n<3 for five young radio pulsars. With an accuracy of 30% orbetter, our model reproduces the age, braking index and third frequencyderivative of the Crab pulsar for a disk accretion rate in the range 3 x 10^16- 10^17 g/s.