New Type Ia Supernova Yields and the Manganese and Nickel Problems in the Milky Way and Dwarf Spheroidal Galaxies

• Published in: The Astrophysical journal 2020-06, Vol.895 (2), p.138
• Main Authors: Kobayashi, Chiaki, Leung, Shing-Chi, Nomoto, Ken'ichi
• Format: Article
• Language: English
• Subjects: Abundance; Astrophysics; Chemical abundances; Chemical evolution; Chromium; Deflagration; Detonation; Dwarf galaxies; Dwarf spheroidal galaxies; Enrichment; Evolution; Explosive nucleosynthesis; Fornax dwarf spheroidal galaxy; Galactic evolution; Galaxies; Galaxy chemical evolution; Magnesium; Manganese; Milky Way; Neighborhoods; Nickel; Nuclear fusion; Nuclear reactions; Nucleosynthesis; Progenitors (astrophysics); Sculptor dwarf elliptical galaxy; Solar neighborhood; Spheroidal galaxies; Stars & galaxies; Supernova; Supernovae; Type Ia supernovae; White dwarf stars; Yield
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ab8e44

In our quest to identify the progenitors of Type Ia supernovae (SNe Ia), we first update the nucleosynthesis yields for both near-Chandrasekhar- (Ch) and sub-Ch-mass white dwarfs (WDs) for a wide range of metallicities with our 2D hydrodynamical code and the latest nuclear reaction rates. We then include the yields in our galactic chemical evolution code to predict the evolution of elemental abundances in the solar neighborhood and dwarf spheroidal (dSph) galaxies Fornax, Sculptor, Sextans, and Carina. In the observations of the solar neighborhood stars, Mn shows an opposite trend to elements, showing an increase toward higher metallicities, which is very well reproduced by the deflagration-detonation transition of Ch-mass WDs but never by double detonations of sub-Ch-mass WDs alone. The problem of Ch-mass SNe Ia was the Ni overproduction at high metallicities. However, we found that Ni yields of Ch-mass SNe Ia are much lower with the solar-scaled initial composition than in previous works, which keeps the predicted Ni abundance within the observational scatter. From the evolutionary trends of elemental abundances in the solar neighborhood, we conclude that the contribution of sub-Ch-mass SNe Ia to chemical enrichment is up to 25%. In dSph galaxies, however, larger enrichment from sub-Ch-mass SNe Ia than in the solar neighborhood may be required, which causes a decrease in [(Mg, Cr, Mn, Ni)/Fe] at lower metallicities. The observed high [Mn/Fe] ratios in Sculptor and Carina may also require additional enrichment from pure deflagrations, possibly as SNe Iax. Future observations of dSph stars will provide more stringent constraints on the progenitor systems and explosion mechanism of SNe Ia.