Pulsar braking indices revisited

Using the standard equation for the slowdown of a neutron star, we derive a formula for the braking index via integration rather than the conventional differentiation. The new formula negates the need to measure the second ti me derivative of the rotation frequency, (nu)double over dot. We show that the method gives similar braking indices for PSR B1509-58 and the Crab puls ar to those already in the literature. We point out that our method is usef ul for obtaining the braking indices of moderate-aged pulsars without the n eed for long, phase-connected timing solutions. We applied the method to 20 pulsars and discuss the implications of the results. We find that virtuall y all the derived braking indices are dominated by the effects of (unseen) glitches, the recovery from which corrupts the value of (nu)over dot. Howev er, any real, large, positive braking index has implications for magnetic f ield decay and offers support to recent models of pulsar evolution.