The strongest magnetic fields in the universe have been simulated on the computer by researchers in the UK and Germany. The fields, which are thousand million million times stronger than the magnetic field of the Earth are produced when two magnetised neutron stars collide. Theory suggests these fields could be the source of violent gamma-ray burst explosions.
Neutron stars have a mass similar to that of our Sun but are just 20 km across, which makes them denser than atomic nuclei. According to the theory of general relativity, two neutron stars orbiting each other will ultimately collide violently.
Daniel Price of the University of Exeter, UK and Stephan Rosswog from the International University of Bremen, Germany, revealed their simulations of this processat at the Royal Astronomical Society’s National Astronomy Meeting on 5th April and at the Ringberg-conference on Nuclear Astrophysics on the 7th April. The results are also published today in Science Express.
“It is only recently that we have the computing power available to model the collisions and take into account the effects of magnetic fields,” explains Price, “It has taken us months of nearly day and night programming to get this project running,” he adds. Everyday magnetic fields produced by domestic electrical products such as the pump in a refrigerator are about 100 Gauss, says Rosswog. The colliding neutron stars produce a field an incredible 10 million million times stronger.
In the supercomputer simulations, Price and Rosswog show that within the first millisecond of the collision, magnetic fields are produced that are stronger than any other magnetic field that is known in the Universe. The calculations are a computational challenge because they include a lot of exotic physics, including effects of high-density nuclear physics, particle physics and General Theory of Relativity. To calculate only a few milliseconds of a single collision takes several weeks on a parallel supercomputer.
Scientists have long suspected that such a collision may be at the heart of some of the brightest explosions in the Universe since the Big Bang, so-called short gamma-ray bursts. Recent detections of ‘afterglows’ of such bursts have confirmed this idea, but much of the physics behind these explosions still lies in the dark. (Boom, Boom!)