Nucleosynthesis Constraints on the Explosion Mechanism for Type Ia Supernovae

TL;DR

This paper compares nucleosynthesis predictions from various Type Ia supernova models with observational data to constrain explosion mechanisms, highlighting the potential of isotopic ratios to distinguish between high- and low-density progenitors.

Contribution

It provides a comprehensive comparison of spherical, cylindrical, and 3D supernova models with observational nucleosynthesis data, proposing that both high- and low-density explosion environments contribute to observed supernovae.

Findings

Models and data tend to cluster into two groups based on density.

Low-density merger models are slightly more consistent with nucleosynthesis data.

High-density deflagration models also fit the observational constraints.

Abstract

Observations of type Ia supernovae include information about the characteristic nucleosynthesis associated with these thermonuclear explosions. We consider observational constraints from iron-group elemental and isotopic ratios, to compare with various models obtained with the most-realistic recent treatment of electron captures. The nucleosynthesis is sensitive to the highest white-dwarf central densities. Hence, nucleosynthesis yields can distinguish high-density Chandrasekhar-mass models from lower-density burning models such as white-dwarf mergers. We discuss new results of post-processing nucleosynthesis for two spherical models (deflagration and/or delayed detonation models) based upon new electron capture rates. We also consider cylindrical and 3D explosion models (including deflagration, delayed-detonation, or a violent merger model). Although there are uncertainties in the observational constraints, we identify some trends in observations and the models. We make a new comparison of the models with elemental and isotopic ratios from five observed supernovae and three supernova remnants. We find that the models and data tend to fall into two groups. In one group low-density cores such as in a 3D merger model are slightly more consistent with the nucleosynthesis data, while the other group is slightly better identified with higher-density cores such as in single-degenerate 1D-3D deflagration models. Hence, we postulate that both types of environments appear to contribute nearly equally to observed SNIa. We also note that observational constraints on the yields of $^{54}$Cr and $^{54}$Fe, if available, might be used as a means to clarify the degree of geometrical symmetry of SNIa explosions.