| Description: | Although pulsars are some of the most stable clocks in the universe, many of them are observed to 'glitch', i.e. to suddenly increase their spin frequency. I will focus on the 'giant' glitches, i.e. glitches with fractional increases in the spin rate of the order of a part in a million that are observed in a sub class of pulsars including the Vela. I will show that giant glitches can be modelled with a two-fluid hydrodynamical approach combined with recent realistic calculations of the pinning forces between superfluid vortices and the crustal lattice in a neutron star. All stages of Vela glitches, from the rise to the post-glitch relaxation, can be reproduced with a set of physically reasonable parameters and the sizes and waiting times between giant glitches in other pulsars are also consistent with the model I will describe. |
