Gamma-ray burst breaks record for biggest cosmic explosion

Washington: Cosmic explosion caused by the death of a star in a distant galaxy became the focus of astronomers around the world after it occurred in April.

The explosion, known as a gamma-ray burst and designated GRB 130427A, has topped the charts as one of the brightest ever seen. A trio of NASA satellites, working in concert with ground-based robotic telescopes, captured never-before-seen details that challenge current theoretical understandings of how gamma-ray bursts work. "We expect to see an event like this only once or twice a century, so we`re fortunate it happened when we had the appropriate collection of sensitive space telescopes with complementary capabilities available to see it," Paul Hertz, director of NASA`s Astrophysics Division in Washington, said. Gamma-ray bursts are the most luminous explosions in the cosmos, thought to be triggered when the core of a massive star runs out of nuclear fuel, collapses under its own weight, and forms a black hole. The black hole then drives jets of particles that drill all the way through the collapsing star and erupt into space at nearly the speed of light. Gamma-rays are the most energetic form of light. Hot matter surrounding a new black hole and internal shock waves produced by collisions within the jet are thought to emit gamma-rays with energies in the million-electron-volt (MeV) range, or roughly 500,000 times the energy of visible light. The most energetic emission, with billion-electron-volt (GeV) gamma rays, is thought to arise when the jet slams into its surroundings, forming an external shock wave. NASA`s Swift Gamma-ray Burst Mission detected the burst almost simultaneously with the GBM and quickly relayed its position to ground-based observatories.