A star like the sun, rotating once per month would rotate about 1000 times per second when contracted down to 10 km in size. Conservation of Angular Momentum Conservation of Magnetic Flux - lines of magnetic force will be carried along with the collapse of the plasma core of the star. The charged particles, accelerated along the curved magnetic field lines produce a type of light called curvature radiation . Whatever the detailed mechanism, radiation near the neutron star poles produces strong, narrow beams of light which sweep around the sky like a tilted lighthouse, as shown below. If the earth lies in the path of the beam we see a pulsar.
Energy is transported from the spinning neutron star into the nebula by the magnetic field.
HST has provided dramatic evidence of the interaction of the Crab Pulsar and the supernova remnant. This Picture of the Day and this HST Press release show the ripples produced by the pulsar moving outward through the nebula, also shown in this MPEG movie . Here is an excellent and detailed Introduction to Neutron Stars by Cole Miller at Chicago. Pulsars are frequently in the news because of their extreme nature and the wide variety of physical processes that may be studied in them. Binary Pulsar which resulted in the award of the Nobel Prize in Physics to Joe Taylor and Russell Hulse, its discoverers.