Simulation of Supernova explosion on Supercomputers
Supernovae occur when nuclear fusion ceases in stars with more than about eight solar masses. The star collapses to a neutron star and a huge amount of gravitational binding energy is liberated and mostly radiated away in the form of neutrinos, which are believed to deposit some of their energy behind the outgoing shock wave, thus powering the explosion. Despite 40 years of research, the details of this mechanism are still not completely understood due to the complex interplay of hydrodynamics, neutrino transport and nuclear physics. Today, large-scale simulations provide more and more insights into the explosion mechanism, the origin of neutron star kicks, and the production of the heavy elements.
The modeling of the neutrino transport in six-dimensional phase space presents a particular numerical challenge. Since the full 3D hydro- and 6D neutrino transport problem would require a sustained performance of 1 to 10 PFlops, which is beyond the current capacity of modern computing facilities, the MPA currently uses a 2D hydro model and a "ray-by-ray-plus" variable Eddington factor method requiring TFlop capability. Successful explosions have already been obtained for some progenitor models in the 8-15 solar mass range with this approximation. Future simulations will cover a broader range of progenitor stars, and also provide important data for nucleosynthesis studies, as well as for neutrino and gravitational wave astronomy.
Entropy and electron fraction during the explosion of an 8.8 solar mass star
(Bernhard Müller, Hans-Thomas Janka, Max Planck Institute for Astrophysics, Garching, Katharina Benkert, HLRS)