Implications of a constant observed braking index for young pulsar's spindown

Abstract

The observed braking index n_{obs} which had been determined for a few young pulsars, had been found to differ from the expected value for a rotating magnetic dipole model. Also, the observational jerk parameter, determined for two of these pulsars, disagree with the theoretical prediction m_{obs} = 15 in both cases. We propose a simple model able to account for these differences, based on a growth of the "torque function" K = -(dot Omega)/(Omega^{n}), under the constraint that n_{obs} is a constant. We show that there is observational evidence supporting the latter hypotesis, and derive initial values for several physical quantities for the four pulsars whose n_{obs} have been measured.