Nucleosynthesis Constraints on the Explosion Mechanism for Type Ia Supernovae

Kanji Mori1,2, Michael A. Famiano3,2, Toshitaka Kajino4,2,1, Toshio Suzuki5,2, Peter M. Garnavich6, Grant J. Mathews5,2, Roland Diehl7,2, Shing-Chi Leung8, and Ken’ichi Nomoto8
The Astrophysical Journal 863, 176 Link to Article [https://doi.org/10.3847/1538-4357/aad233]
1Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
2National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan
3Department of Physics, Western Michigan University, Kalamazoo, MI 49008, USA
4School of Physics and Nuclear Energy Engineering, and Internationsl Research Center for Big-Bang Cosmology and Element Genesis, Beihang University, Beijing 100083, People’s Republic of China
5Department of Physics, College of Humanities and Sciences, Nihon University 3-25-40 Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan
6Departmant of Physics, Center for Astrophysics, University of Notre Dame, Notre Dame, IN 46556, USA
7Max Planck Institut für extraterrestrische Physik, D-85748 Garching, Germany
8Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583, Japan

Observations of type Ia supernovae (SNe Ia) 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 (ECs). 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 EC 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 the 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 SN Ia. We also note that observational constraints on the yields of 54Cr and 54Fe, if available, might be used as a means to clarify the degree of geometrical symmetry of SN Ia explosions.

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