When these inexplicable explosions were first observed in the 1960′s, scientists had little idea about what they were; they were simply way too energetic to be supernovae.
But a GRB is a very different creature to an ‘average' supernova. Via a mechanism that is poorly understood, intense narrow jets of hot plasma are blasted from the dead star's rotational axis. Intense radiation is also produced. If one of those jets are pointing directly at Earth, we'll see an explosion that seems too powerful to be a supernova. That's a gamma-ray burst.
But how is the energy concentrated into a beam - akin to the beam of light emitted by a lighthouse?
According to magnetar theory, when a massive star goes supernova and a magnetar is created, the rapidly spinning and powerful magnetic field of the object will churn up material nearby, drag it in and then blast powerful jets of hot plasma out from the poles.
However, there's another possible GRB mechanism that could generate these powerful jets. If a black hole is created from a collapsed star, it might also stir up surrounding matter, generate jets, firing intense radiation from its poles.