Abstract:
Core collapse supernovae are dramatic explosions of giant stars at the end of their thermonuclear evolution giving birth to neutron stars and black holes. They are among the most energetic phenomena in the universe, play a key role in the formation and spreading of the chemical elements, trigger the formation of new stars, and are closely related to a sub-class of the enigmatic gamma-ray bursts. Hence, astrophysicists have a substantial interest to understand which stars do explode as supernovae, which physical processes cause the explosion, and which are the observable consequences of these cataclysmic events. The optical supernova outburst commences when the explosion wave, generated in the optically obscured stellar center, eventually reaches the surface layers of the star. As giant stars have very large radii, the optical outburst begins only hours after the actual onset of the catastrophe in the very center of the star. There the burnt out stellar iron core collapses due to electron captures and photo-disintegration of heavy nuclei to a neutron star or black hole thereby liberating the energy which causes the explosion. The only means to get direct and immediate information about the supernova "engine" is from observations of neutrinos emitted by the forming neutron star, and through gravitational waves which are emitted when the collapse does not proceed perfectly symmetrically. Numerical simulations exploiting the most powerful supercomputers provide a third way to study the complex supernova phenomenon. In the talk I will discuss both the physical processes leading to and causing a core collapse supernova, and present some exciting results from recent core collapse supernova simulations.

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