The Whipple Telescope Studies Gamma Ray Bursts
Tuesday, January 30, 2007
Science Update - A look at CfA discoveries from recent journals

Gamma ray bursts (GRBs), the brightest events in the known universe, are flashes of high-energy light that occur about once a day, randomly, from around the sky. While a burst is underway, it is many millions of times brighter than an entire galaxy. Astronomers are anxious to decipher their nature not only because of their dramatic energetics, but also because their tremendous brightnesses should enable them to be seen across cosmological distances and times.

The circumstantial evidence on GRBs to date suggests that radiation from the gigantic explosions is beamed (that is, it is not radiated uniformly in all directions), and that shocks from ultra-fast moving particles produce much of the emission. Some models predict that hours or days after the explosion itself more gamma rays are produced by shock activity; some of this radiation is expected to have particularly high energy, hundreds of thousands of times more than medical X-rays, for example.

Two SAO astronomers, Deirdre Horan and Trevor Weeks, led a team of fifty-nine scientists in a study of gamma-ray bursts using the ten-meter Whipple Telescope on Mt. Hopkins, Arizona, one of the few facilities in the world capable of studying such very high energy radiation. When a GRB event was detected by an orbiting satellite, the email announcement triggered a flurry of telescope activity; bursts fade quickly, after all, and putative aftershocks might only last for a day. The Whipple Telescope is in principal able to slew and stare at any part of the visible sky in only three minutes, and its rapid response makes it ideal for GRB research. Over a seventeen month period spanning 2003, it studied seven different GRBs. While not detecting any very high energy radiation from these seven bursts, its precision was able to set useful constraints on some of the models of GRB, and to refine techniques for future observations. Considering that GRBs produce the most dramatically energetic events in the universe, it is expected that these very high energy investigations will help to refine our understanding of physics and the nature of matter in extreme conditions.