• November 17, 2005

    Episode 10: Short Gamma Ray Bursts

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    For 35 years, the origin of the powerful, split-second flashes of light known as short gamma-ray bursts has been a mystery. Short gamma ray bursts are intense flashes, brighter than a billion suns, that last only a few milliseconds. They're difficult to study because they happen so quickly, without warning, anywhere in the sky. Catching one is like being in a crowd and having a camera flash go off behind your back. You can't turn fast enough to detect where the flash came from. Two years ago, scientists discovered long gamma ray bursts, lasting more than two seconds, that arise from the explosion of massive stars. But about 30 percent of gamma ray bursts are shorter than that. Observations by a number of satellites have helped resolve this puzzle. The recently launched Swift satellite detected a short burst on May 9, 2005, and the Chandra X-Ray Observatory observed -- for the first time ever -- its afterglow. NASA's High-Energy Transient Explorer detected another burst on July 9, 2005. The burst and afterglow suggest a violent collision. Scientists now believe that short gamma ray bursts result from collisions between either a black hole and a neutron star or two neutron stars. In either scenario, the impact creates a new black hole, releasing a terrific amount of energy.