24 SEP. 2002
publication date
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Astronomical satellites register sudden bursts of gamma rays, always from a random direction, roughly once a day. These bursts may last a hundredth of a second, or anything up to 90 minutes. They become, briefly, the brightest objects in the gamma-ray sky but are never seen to repeat.
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An image of the full sky, showing gamma rays from radioactive aluminium, produced in supernovae
For over 20 years, astronomers had no clues about how far away these explosions occurred. Until in 1997, the Italian-Dutch satellite BeppoSAX provided accurate X-ray measurements so quickly that a burst’s location could be pinpointed, enabling follow-up observations with optical and other telescopes.
These observations confirmed that the gamma-ray bursts are extremely distant and therefore must be caused by tremendous explosions equal to the radiance of millions of millions of stars.
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Gamma-ray burst captured by Integral
Where does this energy come from? This colossal amount of energy may be released when compact objects, such as neutron stars or black holes, collide. Astronomers know of a number of neutron stars in our galaxy that are in orbit around one another and may merge in the far future.
There is also mounting evidence that incredibly powerful supernovae, called ‘hypernovae’, are the source of the gamma-ray bursts.
During its many years of observations, Integral looked at the glowing debris for the telltale signs of elements created when a star explodes.
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Integral overview
Name: Integral (International Gamma-Ray Astrophysics Laboratory)Status: Completed (launched on 17 October 2002, stopped collecting scientific data on 28 February 2025)Mission theme: Tracking violent events across the Universe
Integral science highlights
The International Gamma-Ray Astrophysics Laboratory (Integral) has provided unprecedented information about the Universe’s most exotic objects. It has revealed how matter behaves under extreme conditions and helped astronomers understand processes such as the formation of new chemical elements and mysterious gamma-ray bursts. These findings have been documented in an impressive, and growing, body of scientific and popular literature.
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