Consider a collapsing star with a strong magnetic field. It matters not whether the star is a neutron star, white dwarf, or whatever.

As the star collapses into a black hole, it runs into a theorem, "a black hole has no hair", in other words, there are no characteristics of a black hole other than mass, angular momentum, and electric charge. In particular, no magnetic field can penetrate the event horizon.

Stellar magnetic fields are generated by vast electrical currents within the star's interior. During collapse, a significant fraction of the gravitational energy of collapse must be used to compress the magnetic field and remains locked within the field until the event horizon forms.

However, the instant that the event horizon forms, the generating currents are essentially cut off from our Universe. Thus, the intense magnetic field of the star must be ejected violently from the body of the star. The field is suddenly cut loose from its source, but cannot simply cease to exist. It must follow Maxwell's Equations and explode at the speed of light. In doing so, it will run into the outer layers of the star along with the accretion disk (if any) surrounding the star. The intensity of the expanding field will accelerate the nuclei of these atoms to ultra-relativistic energies, cosmic ray primaries.

Some of these energetic nuclei will collide with "stationary" nuclei and ultra-relativistic neutrons (and other neutral baryons along with gamma rays) will be produced. While the braking effect of the cosmic microwave background radiation slows down the charged primaries to the Greisen-Zatsepin-Kuzmin limit, it has no effect on the uncharged neutrons. Proper time for these ultra-relativistic neutrons is diminished at the same ratio as rest mass to total mass-energy. Thus, an ultra-relativistic neutron will experience time quadrillions of time slower than a neutron at rest. These neutrons can thus travel all over the Universe in less than a second of proper time, so that they do not decay. When they strike the upper atmosphere of the Earth, they produce the high energy cosmic ray secondary showers that are reported.

The concept of flux ejection explains both the source of gamma ray bursts as well as the ability of ultra high energy cosmic rays to circumvent the Greisen-Zatsepin-Kuzmin limit.