# Brighter than a billion suns

### Scientists at Albert Einstein Institute calculate the first complete relativistic simulation of colliding neutron stars

October 24, 2008

What happens exactly when two neutron stars collide and form a black hole? How much energy is released in this event? Is this the way in which the enigmatic gamma-ray bursts are produced? The numerical-relativity group at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute, AEI) has now answered these questions and published the first complete and accurate simulations of this complex process in three dimensions and under full conditions of general relativity. The results yield important information both for gravitational wave- and for gamma-ray burst-researchers and hence to a deeper understanding of our universe. The paper was now published in the scientific journal Physical Review D.

These calculations, whose complexity requires the use of the most advanced parallel computers, were performed using the specially dedicated supercomputers at the AEI: BELLADONNA and DAMIANA.

„Our calculations provide the clearest predictions yet of how two neutrons stars merge together.” says Prof Luciano Rezzolla, head of the numerical-relativity group at AEI. “Neutron stars are extremely fascinating objects and, when compared to black holes, their physics is much more interesting and rich. Our calculations of their behaviour provide new information about the gravitational waves emitted, but also about short gamma-ray bursts (or GRBs), some of the most energetic and mysterious astrophysical explosions”

Prof. Bernard Schutz, Managing Director of the AEI adds: “The results obtained by Prof. Rezzolla’s group represent a very important step in understanding collisions of neutron stars. The group has worked for many years to develop the most powerful software tools, and they have been supported by the Max Planck Society with some of the fastest computers available for this kind of research. This long effort has led to today’s breakthrough result. We finally have a simulation that uses all the physics of Einstein’s general relativity to study fully these rare but extremely powerful events.”