Monster explosion: The gamma-ray burst's X-ray afterglow appears orange and yellow in this view that merges images from Swift's UltraViolet/Optical and X-ray telescopes.

Credit: NASA/Swift/Stefan Immler

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"It's thought that something involved in spinning up and collapsing into that black hole in the centre is what drives these jets. No one really has figured that out. The jets rip through the star and the supernova follows after the jets," Reddy said.

Studying gamma-ray bursts allows scientists to "sample an individual star at a distance where we can't even see galaxies clearly," Reddy said.

Space enigma

Observing the massive explosions could also lift the veil on more of space's enigmas, including those raised by the burst spotted by Fermi, such as a "curious time delay" between its highest and lowest energy emissions.

Such a time lag has been seen in only one earlier burst, and "may mean that the highest-energy emissions are coming from different parts of the jet or created through a different mechanism," said Stanford University physicist Peter Michelson, the chief investigator on Fermi's large area telescope.

"Burst emissions at these energies are still poorly understood, and Fermi is giving us the tools to understand them. In a few years, we'll have a fairly good sample of bursts and may have some answers," Michelson said.

The Fermi telescope and NASA's Swift satellite detect "in the order of 1,000 gamma-ray bursts a year, or a burst every 100,000 years in a given galaxy," said Reddy. Astrophysicists estimate there are hundreds of billions of galaxies.