Evidence for Sub-Chandrasekhar Type Ia Supernovae from Stellar Abundances in Dwarf Galaxies
Abstract
There is no consensus on the progenitors of Type Ia supernovae (SNe Ia) despite their importance for cosmology and chemical evolution. We address this question using our previously published catalogs of Mg, Si, Ca, Cr, Fe, Co, and Ni abundances in dwarf galaxy satellites of the Milky Way (MW) to constrain the mass at which the white dwarf (WD) explodes during a typical SN Ia. We fit a simple bi-linear model to the evolution of [X/Fe] with [Fe/H], where X represents each of the elements mentioned above. We use the evolution of [Mg/Fe] coupled with theoretical supernova yields to isolate what fraction of the elements originated in SNe Ia. Then, we infer the [X/Fe] yield of SNe Ia for all of the elements except Mg. We compare these observationally inferred yields to recent theoretical predictions for two classes of Chandrasekhar-mass (M Ch) SN Ia as well as sub-M Ch SNe Ia. Most of the inferred SN Ia yields are consistent with all of the theoretical models, but [Ni/Fe] is consistent only with sub-M Ch models. We conclude that the dominant type of SN Ia in ancient dwarf galaxies is the explosion of a sub-M Ch WD. The MW and dwarf galaxies with extended star formation histories have higher [Ni/Fe] abundances, which could indicate that the dominant class of SN Ia is different for galaxies where star formation lasted for at least several Gyr.
The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 2019
- DOI:
- 10.3847/1538-4357/ab2c02
- arXiv:
- arXiv:1906.10126
- Bibcode:
- 2019ApJ...881...45K
- Keywords:
-
- galaxies: abundances;
- galaxies: dwarf;
- Local Group;
- nuclear reactions;
- nucleosynthesis;
- abundances;
- supernovae: general;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted to ApJ on 2019 June 22. 21 pages, 9 figures. This is a companion paper to arXiv:1906:08284. Figure 6 presents the main result. Minor proof corrections in v2