A neutron star is an extremely dense, rapidly rotating star that remains after some supernova explosions. Galactic primaries may also gain energy from weaker waves that travel along the weak magnetic fields of interstellar space. The most powerful source of energy is supernova shock waves. However, the highest-energy primaries have more energy than even a supernova can provide. Scientists do not know how these particles get their extra energy.
Magnetic fields control the travel of cosmic rays through space.
A magnetic field can be thought of as a set of imaginary lines extending through space. No field line crosses another. In outer space, where magnetic fields are weak, a field line may be stretched many trillions of miles from its source. It is often not clear where these fields originate. Charged particles therefore can move easily along a magnetic field but have difficulty traveling very far across a field.