Swift and the Gamma-ray Bursters

Swift Discovers 500th Burst

This all-sky map shows the locations of the 500 gamma-ray bursts Swift has detected. Credit: NASA/Swift.

In 2004, NASA launched the Swift satellite to study explosive, high-energy events in the universe. Five years later, the spacecraft has recorded its 500th burst. This satellite was launched to study these strong, distant explosions, some of which are thought to occur when two neutron stars in a binary system merge, sending out a pulse of gravitational waves and what’s called a short gamma-ray burst.

Swift’s job is to focus on a burst and report its position so that other observatories can immediately start to study the phenomenon. As soon as it alerts observers, the satellite then focuses on the same explosion with an array of x-ray and ultraviolet/optical-sensitive telescopes. The resulting data are giving astronomers a much better sense of where these outbursts are occurring and a clearer look at the characteristics of each explosion (that is, the light-curves they exhibit).

Swift also studies other explosive events in the universe, such as exploding stars (supernovae, for example), outbursts from the regions near black holes, and high-energy surges from neutron stars. It is also doing a long-term survey of the entire sky in x-ray wavelengths.

Gamma-ray bursters are extremely fascinating to astronomers. This is because gamma-rays themselves are signals from the highest-energy types of events in the cosmos. A gamma-ray burster is a sign that something extremely energetic has occurred. What could it be? The answer to that question kept astronomers busy for years, coming up with models to explain just what kind of event could trigger such an energetic explosion.  Some key breakthroughs came in 1997 when an Italian-Dutch satellite called Beppo-SAX provided very precise locations for some gamma-ray bursters. From that data, astronomers could zero in on the sources and spend time figuring out what the sources of the burst were.  It was a cosmic detective story that Swift is continuing to follow up on. For more information on the 500th burst, check out the NASA press release.

In addition, I’m working on a special June 2010 segment of The Astronomer’s Universe about gamma-ray bursters, so stay tuned for more on these bright, formerly mysterious explosions that seem to come at us from every direction of the cosmos!