(2) The Crab Nebula supernova was caused by the star collapsing on itself due to the loss of the heat and pressure that was being generated by the hydrostatic compression of the nuclear fuel in the core of the star. Because of that, the star imploded down to the size and density of a neutron star where it re-exploded upon reaching a critical mass, much like in a nuclear bomb detonation.

(3) The 20 km wide core of the Crab Nebula supernova still remains spinning extremely rapidly in the form of a condensed neutron star.
(4) The rapidly spinning of neutron stars is caused by the conservation of angular momentum resulting from the collapse of the original progenator star, much like an ice figure skater pulling her arms inward toward her body while doing a spin maneuver. The rapid spinning of the neutron star in combination with the superfluous rotation or circulation of the outer proton core generates a really strong magnetic field vector (on the order of 10^8 teslas) which has an axial direction offset from the star's main rotation axis.
(5) The rapid spinning of the neutron star in the Crab Nebula causes the star to emit a strong pulse of electromagnetic x-ray radiation in our direction, similar to a cosmic a light house rotating at a rate of 30 hertz. Here is the view of the Crab Nebula pulsar in the X-ray light spectrum.

Source:
