Friedrich Roepke (UCSC and MPA Garching)
Abstract:
The application of Type Ia supernovae as distance indicators led to the spectacular discovery of the currently accelerated expansion of the universe. This points to a dominating Dark Energy component and Type Ia supernovae are one of the most promising tools to constrain the nature of this mysterious energy form.
But what are these objects? Although there is consensus about the general astrophysical scenario -- a white dwarf star undergoing a thermonuclear explosion -- details of the explosion process remain unclear. Uncertainties in the ignition and the flame propagation mechanism lead to different options in constructing models. Does the flame ignite centrally or off-center? Can it undergo a transition from a subsonic to a supersonic propagation mode? Recent progress in numerical techniques and the constant advancement of supercomputers facilitate three-dimensional simulations testing the impact of these options on the explosion process. Due to the high predictive power of these simulations, observables derived from the models can be directly confronted to observations. This way, a validation of the model has come into reach and I will report on the status of this project. The ultimate goal is to develop a valid and self-consistent Type Ia supernova explosion model which can than be used to tackle the questions arising in supernova cosmology making these measurements more reliable. This approach will be discussed on the basis of an illustrative example.