The Hunt For Cosmic Blasts' Secret

[zavvy]

<b>The Hunt For Cosmic Blasts' Secret</b><br /><br />LINK<br /><br />One of the most mysterious and explosive phenomena in the Universe could finally yield its secrets when Nasa launches its space mission Swift. <br /><br />Gamma-ray bursts can release as much energy in a few minutes as the Sun emits in its 10-billion-year lifetime. <br /><br />Yet what causes these mighty blasts is still unknown, UK scientists explained at a news conference in London on Monday. <br /><br />The $250m probe, whose launch in Florida was delayed by hurricanes, could lift off on 11 November at the earliest. <br /><br />"The source of gamma-ray bursts is a long-standing detective story in modern astronomy," said Professor Keith Mason, of the Mullard Space Science Laboratory (MSSL) in London and lead investigator for the Ultraviolet-Optical Telescope on Swift. <br /><br />Professor Martin Ward, chair of the science committee for the Particle Physics and Astronomy Research Council (Pparc), commented: "They are the biggest bangs since the big one." <br /><br />Black-hole sun <br /><br />Scientists think that gamma-ray bursts are generated in two principal scenarios. In one scenario, a star collapses in on itself, giving birth to a black hole. <br /><br />As stars reach the end of their life, the nuclear reactions in their cores stop. This removes the radiation pressure that keeps the star inflated, so that the core of the star collapses inwards and forms a black hole. <br /><br />Material is sucked in towards the black hole and begins to circle it at high velocity. This causes a powerful jet to burst from the torrent, carrying material moving at close to the speed of light. It is this jet that carries the radiation detected on Earth as gamma-ray bursts. <br /><br />"This jet contains huge amounts of energy, much of which is converted to electromagnetic radiation; gamma rays, X-rays or optical light," said Prof Mason. <br /><br />"Becau