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Imagine watching twin stars move 37 miles in a matter of milliseconds, collide, spew out radiation and form an object so massive it collapses on itself and forms a black hole.
It's a sight scientists at Brigham Young University have seen a hundred times - in the yellows, blues and reds generated by the 106th-fastest supercomputer in the world.
Such simulations help guide astrophysicists tracking down objects that don't emit light, such as black holes, and BYU's model, which will appear in today's issue of the scientific journal Physical Review Letters, takes into account one factor most don't: the magnetic fields of stars.
More than half of all stars are twins that share a solar system, such as those seen on Luke Skywalker's fictional planet, Tatooine, in "Star Wars." If at least one of the stars is very large, then both will explode in a supernova when they run out of fuel. The burned-out cores left behind, called neutron stars, are so dense they cause gravitational ripples in space as predicted by Einstein's theory of general relativity. Tracking such events will be "a really good test" of that theory, said study co-author David Neilsen, associate professor of physics.
Along with Neilsen, BYU's Eric Hirschmann and Matthew Andersen, collaborators from Louisiana State University and Long Island University focused on what happens when two neutron stars pull each other together. They found the stars' magnetic fields slow down the merger, allowing one extra orbit during the final 12 milliseconds. That may seem insignificant, but that delay increases the energy radiated by gravitational waves so they are more easily found.
"To detect black holes, you have to know exactly what to look for. When the magnetic fields slowed down the star collisions, there was more energy there and [it] made them easier to detect," Neilsen said. "It also changed slightly what you need to be looking for."
The inclusion of stars' magnetic fields is important because the more accurate the simulation, the closer science comes to explaining deep-space mysteries like gamma-ray bursts, which occur when a black hole forms.
"The origin of gamma-ray bursts has been a mystery for 40 years, and the fireballs created in the mergers of neutron-star pairs or neutron star-black hole pairs have emerged as the most likely sources of short gamma-ray bursts," said John Friedman, a physics professor at the University of Wisconsin-Milwaukee who was not involved in the study. "The code developed by this collaboration brings us one step closer to resolving this mystery."
* Watch a video simulation of neutron stars colliding: http://byunews.byu.edu/releases/archive08/May/stars/Blackhole3.mov" Target="_BLANK">http://byunews.byu.edu/releases/archive08/May/stars/Blackhole3.mov