OBSERVATIONAL CONSTRAINTS ON THE INTERNAL STRUCTURE AND DYNAMICS OF THE VELA PULSAR

We show that the short spin-up time observed for the Vela pulsar durin g the 1988 ''Christmas'' glitch implies that the coupling time of the pulsar core to its crust is less than similar to 10 s. Ekman pumping c annot explain the fast core-crust coupling and a more effective coupli ng is necessary. The internal magnetic field of the Vela pulsar can pr ovide the necessary coupling if the field threads the core with a magn itude that exceeds 10(13) G for a normal interior and 10(11) G for a s uperconducting interior. These lower bounds favor the hypothesis that the interior of neutron stars contains superfluid neutrons and protons and challenge the notion that pulsar magnetic fields decay over milli on year timescales or that magnetic flux is expelled from the core as the star slows.