Supernova Explosions Wolfgang Bauer

Two of the most prominent ways to model the time evolution of complex many-body systems are hydrodynamics and kinetic theory. Over the last two decades, MSU University Distinguished Professor Wolfgang Bauer has made several contributions to the kinetic theory based description of subatomic reactions and has advanced our understanding of experiment observables in high and medium energy heavy ion reactions. In particular, his work has led to a deeper understanding of the nuclear equation of state and phase transitions of nuclear matter in finite size systems.

Now Prof. Bauer is applying his techniques and computer models to systems of vastly different length, mass, and time scales: the supernova explosions of massive stars at the end of their live. Modeling supernova explosions has long been the domain of hydrodynamics. However, these explosions are, to a large degree, driven by neutrinos. These neutrinos can have a very long mean free paths due to their very small interaction probabilities and are thus not in the domain of validity of hydrodynamics. The conventional way to remedy this shortcoming is to couple hydrodynamics to a neutrino Boltzmann transport calculation. Bauer's answer is much more straightforward: apply kinetic theory, which is free of assumptions about the mean free paths, to all matter constituents, baryons as well as neutrinos. In his approach, he and his research group simultaneously solve billions of coupled first-order differential equations in time for so-called test particles, which make their work an ideal candidate for massively parallel multi-processor environments such as those provided by iCER's High Performance Computing Center.