Various theories exist on why space telescopes capture images of gamma ray bursts, many of them literally flashes of light. In EU theory it is down to electricity in the universe but in mainstream it is not as clear cut (as far as an explanation is concerned). At https://phys.org/print443091109.html … which concerns a paper in the Monthly Notices of the Royal Astronomical Society (2018) DOI:10.1093/mnas/sty013 … where a core collapse supernova explanation is considered, where it is thought the iron core of a star collapses under the force of 'gravity' and then rebounds, generating pressure waves and shocks that project outwards. A superluminous supernova involves core collapse theory – but it seems there are problems with this idea. The source of the energetics is fiercely contested, we are told. The most favoured model is the sustained injection of energy from a source like a spinning compact remnant – a neutron star or an accreting black hole. Long duration gamma ray bursts can last up to several minutes – but most of them last a few seconds.
As such, a unifying model has been proposed in that a spinning neutron star has a slight misalignment between its spin axis and its magnetic axis. In this proposal a substantial fraction of the spinning power are supplied both to the supernova and to a jet of particles moving at speeds close to the speed of light than enable the longer bursts. The EU model appears quite practical in contrast – but words are not enough.