Neutron Star Collisions Create Largest Magnetic Fields Known in Universe

Stephan Rosswog, Professor of Astrophysics at IUB, and Daniel Price, Postdoc at the University of Exeter, for the first time were able to demonstrate in supercomputer simulation of a neutron star merger that a collision of these super dense cosmic objects create magnetic fields a quadrillion (10¹⁵) times stronger than the magnetic field of the earth. The simulation results are published in the current online express issue of Science ("Producing ultra-strong magnetic fields in magnetized neutron star mergers", 30 MARCH 2006).

[ Mar 30, 2006]  Neutron stars are cosmic relics of supernova explosions with extreme high density: In mass comparable to our sun their radius of about 10 km is 70,000 times smaller than that of the sun. When Neutron stars orbit around each other in binary systems, they slowly spiral in towards each other. Their final fate is a thunderously violent collision. It has long been suspected that such a collision may be at the heart of some of the brightest explosions in the universe since the Big Bang, known as 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.

The simulations of Stephan Rosswog and Daniel Price are a first step towards shedding light on the complex Gamma-ray burst physics. Taking into account several fields of the discipline, including effects of high-density nuclear physics, particle physics and General Theory of Relativity, the two astrophysicists computed the first 11 milliseconds of a neutron star collision, which presented a high computational challenge. According to their results within the first millisecond the original magnetic fields of the neutron stars are boosted gigantically to more than 10¹⁵ Gauss.

"These are incredible dimensions ", Stephan Rosswog comments the simulation results. "Magnetic fields that we are familiar with, say from a magnet at a refrigerator, have strength of about 100 Gauss." For the simulation the two scientists used IUB’s parallel-processing supercomputer that had been put into operation the previous year and is one of the most powerful of its kind. "It is only recently that we have the computing power available to model the collisions and take into account the effects of magnetic fields. It has taken us months of nearly day and night programming to get this project running. The actual computing then took almost another month," Daniel Price said about the complex computing.

The two astrophysicists will present their results also at the Royal Astronomical Society's National Astronomy Meeting (NAM 2006) at the University of Leicester on April 5, and at the Ringberg conference on Nuclear Astrophysics on April 7.

For further information as well as downloads of images and animations of the simulation results see
http://www.faculty.iu-bremen.de/srosswog/Magnetic_NSM/.