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

Abstract

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 α 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-Chmass 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.

Predictions for the angular dependence of gas mass flow rate and metallicity in the circumgalactic medium

“…Better measurements will also indirectly help constrain stellar population yields (e.g. Kobayashi, Leung & Nomoto 2020), particularly as more complete treatments of the relevant chemistry become common in cosmological simulations (Ploeckinger & Schaye 2020).…”

The S2 Stream: the shreds of a primitive dwarf galaxy.*

“…However, Mn and Ni show a slightly different behaviour, with higher dispersion with metallicity and the largest overabundance in the iron-peak family. Theoretical studies on SN Ia yields by Kobayashi et al (2020) show an anticorrelation of -elements with Mn and lower Ni production in dwarf galaxies. We do not see Fig.…”

Explosive Nucleosynthesis in Near-Chandrasekhar Mass White Dwarf Models for Type Iax Supernovae: Dependence on Model Parameters

“…Besides SNRs, the nucleosynthesis results presented in this work can be further applied to galactic chemical evolution (e.g., Matteucci & Greggio 1986;Pagel 1997;Kobayashi et al 2020) to identify the role of individual types of SNe to the trend formation of specific elements as a function of metallicity. In particular, SNe Iax can be important in dSphs, where the star formation history can be very different from ordinary galaxies.…”

“…The unique abundance pattern by SNe Iax can leave observable effects. For example, in models for dSph (Kobayashi et al 2015(Kobayashi et al , 2020Cescutti & Kobayashi 2017)…”

“…The SNe Ia are also the major channel for ironpeak element production (e.g., . The role of SNe Ia can be seen in the galactic chemical evolution, including the [α/Fe] versus [Fe/H] relation (Nomoto et al 2013) and the [Mn/Fe] versus [Fe/H] relation (Seitenzahl et al 2013;Kobayashi et al 2020;.…”