New Insights into Type Ia Supernova Explosions from Large-Scale Simulations Don Q. Lamb, University of Chicago

We report new insights into the way in which Type Ia supernovae explode from large-scale simulations carried out at the DOE NNSA ASC/Alliance Flash Center at the University of Chicago. We summarize extensive work we have done to verify our treatment of physical processes important in Type Ia supernovae, particularly turbulent nuclear burning driven by the Rayleigh-Taylor instability. We then describe the results of extensive 2-D and 3-D simulations of the gravitationally confined detonation (GCD) mechanism for Type Ia supernovae, including both the deflagration and detonation phases. In this mechanism, ignition occurs at one or several off-center points, resulting in a burning bubble of hot ash that rises rapidly, breaks through the surface of the star, and collides at a point opposite breakout on the stellar surface. We find that detonation conditions are robustly reached in our 2-D and 3-D simulations for a range of initial conditions and resolutions. These conditions are achieved as the result of an inwardly-directed jet that is produced by the compression of unburnt surface material when the surface flow collides with itself at the opposite point on the stellar surface. A high-velocity outwardly-directed jet is also produced. We discuss recent observations of Type Ia supernovae that imply properties that are consistent with those expected from our 2-D and 3-D simulations of the GCD mechanism.