Ascertaining the Core Collapse Supernova Explosion Mechanism: Dream Becoming Reality

The death throes of massive stars in what are known as core collapse supernovae are a key link in our chain of origin between the Big Bang and the present. They are the dominant source of elements in the Periodic Table between oxygen and iron and among the leading candidates for the production of half the elements heavier than iron. How they occur is key to the emergence of life in the Universe. Core collapse supernovae are three-dimensional, multi-physics events. Their macroscopic behavior is governed by the equations of general relativistic (neutrino) radiation magneto-hydrodynamics, and the microscopic, weak- and strong-interaction physics governing the neutrino interactions in the stellar core and the core's thermodynamics, respectively, are equally important. We will discuss the physics known to be important in core collapse supernovae and discuss how the supernova’s microscopic and macroscopic “worlds” are interdependent. We will present the results from recent two- and three-dimensional simulations and discuss their ramifications for ascertaining the core collapse supernova mechanism and future simulation efforts. Definitive simulation of core collapse supernovae is an exa-scale Grand Challenge. We will discuss a staged effort, beginning with the foundation laid to date, in which three-dimensional simulations of increasing sophistication will be performed over the next decade in order to ascertain the explosion mechanism and to make predictions for important associated observables such as the synthesis of the elements mentioned above, the production of neutrino and gravitational wave signatures, the production of neutron star kicks and spins, and the production of signatures across the electromagnetic spectrum. Neutrino and gravitational wave signatures can in turn be used to learn about fundamental neutrino and nuclear physics, some of which will be inaccessible in terrestrial experiments. We will highlight the key computations underpinning the solution of the system of nonlinear, coupled partial differential equations governing the dynamics of the exploding star and the need for the development of efficient solution algorithms. Despite the obvious challenge, progress is being made, steadily and systematically. Supercomputer architectures are advancing rapidly, and ascertaining the core collapse supernova explosion mechanism is now more than just a pipe dream. Ground- and space-based observatories, some of them opening entirely new branches of astronomy – e.g., LIGO and Gravitational Wave Astronomy – are becoming more and more sophisticated and promise to bring us ever more detailed, and new, information about the explosive stellar environments we study, down to the deepest regions where the central engine operates. Detailed observations of a Galactic core collapse supernova, in neutrinos, gravitational waves, and across the electromagnetic spectrum, against which we will be able to compare our models, will speak volumes. We must prepare! It is truly an exciting time to be a core collapse supernova modeler.​