INTEGRAL

Scientific goal

The scientific goal of the INTEGRAL mission was to understand the Universe’s most violent events. This requires studying:

• Stellar mass compact objects such as neutron stars, black holes, white dwarfs, high-energy transients and gamma-ray bursts.
• Objects outside our Milky Way such as galaxy clusters, cosmic diffuse background and galaxies with an active core (AGN), for example Seyfert galaxies and blazars.
• Nucleosynthesis in stars at the end of their life, both for low-mass stars that swell up to become red giants and for massive stars that explode in a supernova.
• Structure of the Milky Way through mapping of the continuum and emission spectrum.
• Serendipitous sources like the electromagnetic counterpart of the first gravitational wave source identified as a merger between two neutron stars, or the simultaneous emission of gamma rays and a fast radio burst from a magnetar—a highly magnetized neutron star.

Gamma-ray bursts

The Universe continuously sparkles with bright flashes of gamma rays—the highest energetic radiation that exists. These bursts are caused by exploding stars or colliding neutron stars. A heavy star that collapses under its own gravity at the end of its life produces a so-called supernova, which is sometimes accompanied by a gamma-ray burst lasting several seconds. Neutron stars colliding with each other produce much shorter gamma-ray bursts of less than a second or even a few milliseconds.

To learn more about the underlying mechanism, astronomers want to have a picture of before and after. When INTEGRAL’s X-ray and gamma-ray cameras detect a flash, astronomers search the data from the optical camera to view the object that was at the same location on the sky before. This paints the whole picture of the phenomenon of gamma-ray bursts.