GLITCHES, TORQUE EVOLUTION AND THE DYNAMICS OF YOUNG PULSARS

The Crab pulsar has suffered, in 1975 and 1989, two glitches in which the frequency did not relax to the extrapolated pre-glitch value but r ather spun up, showing longterm changes in the frequency derivative (O mega) over dot. This particular behaviour has been interpreted as evid ence for evolution of the torque acting upon the star. A variable torq ue may be related to non-canonical braking indices, for which some det erminations have been possible. We briefly analyse, in this work, the consistency of postulating a growth in the angle between the magnetic moment and the rotation axis as the cause of such events. We show that this hypothesis leads to the determination of the initial period and initial and present angles, according to the assumed angle growth, for young pulsars whose respective braking indices n(obs) and jerk parame ters m(obs) are known, and provides some insights on the equation of s tate.