Astronomy Colloquium

Core-collapse supernovae from massive stars are among the most energetic events in the universe. They liberate a mass-energy equivalent of ~15% of a solar mass in the collapse of their progenitor star's core. The majority (~99%) of this energy is carried away by neutrinos, while (~1%) is transferred to the kinetic energy of the explosive outflow. A smaller, yet still tremendous amount of energy is emitted in electromagnetic and gravitational waves. In 1934, Baade and Zwicky proposed that a "[...] super-nova represents the transition of an ordinary star into a neutron star". 78 years and one core-collapse supernova (SN 1987A) in the Large Magellanic Cloud later, our understanding of core-collapse supernovae is still very incomplete. In particular, the details of the physical process(es) responsible for converting the gravitational energy liberated in collapse into energy of the explosion are still uncertain. I review the current state of core-collapse supernova theory and discuss recent progress made and insights gained from new multi-dimensional computational models. These models are yielding new predictions for the signature of core-collapse supernovae in neutrinos and gravitational waves and I outline how their observation from the next nearby core collapse event can shed light on the supernova mechanism. While a key goal is to understand the mechanism driving regular supernova explosions, a core-collapse supernova is not always the outcome of collapse. I delineate the ensemble of alternative outcomes and present new results on stellar-mass black hole formation and on the core-collapse supernova -- long GRB connection.