Saturday, April 9, 2011
40-Year-Old Mystery of Massive Gamma-Ray Burst Solved
Studies have shown that neutron stars often exist as pairs on the fringes of galaxies, and that they collide frequently, sometimes involving a black hole, also a stellar remnant but one that is much more dense. Neutron stars are often as small as the island of Manhattan with a teaspoon of its material weighing several tons.
A German supercomputer cluster at the Albert Einstein Institute in Germany models events that unfold in just 35 milliseconds -- three times faster than the blink of an eye, has finally solved the Gamma-ray burst mystery by showing that colliding neutron stars can produce magnetic structures which are responsible for the cosmic event, says a NASA study.
Gamma-ray bursts are among the most energetic cosmic events known, emitting as much energy in a few seconds as our entire galaxy does in a year, most of it in the form of Gamma rays, the highest energy form of light.
"For the first time, we''ve managed to run the simulation well past the merger and the formation of the black hole," said the study''s co-author Chryssa Kouveliotou at the US space agency''s Marshall Space Flight Center in Huntsville. "This is by far the longest simulation of this process, and only on sufficiently long timescales does the magnetic field grow and reorganize itself from a chaotic structure into something resembling a jet," she added.
GRBs lasting longer than two seconds are widely thought to be triggered by the collapse of a massive star into a black hole. As matter falls toward black hole, some of it forms jets in the opposite direction that move near the speed of light and produce a blast of Gamma rays as they emerge.
"For more than two decades, the leading model of short GRBs was the merger of two neutron stars. Only now can we show the merger of neutron stars actually produces an ultrastrong magnetic field structured like jets needed for a GRB," Bruno Giacomazzo at NASA''s Goddard Space Flight Center said.