Speaker
Description
A core-collapse supernova (CCSN) is an explosion of a massive star at the end of their life. The explosion mechanism has not yet been clarified in spite of studies for long time. In this study, we focus on nucleosynthesis as a clue to understand the explosion mechanism. Because CCSNe have driven chemical evolution of the Universe, metal-poor stars born in the early Universe remain the nucleosynthesis results of CCSNe of first stars. Therefore, it is one of the important challenges in nucleosynthesis simulations to reproduce the chemical compositions of metal-poor stars. Recent observation shows correlations among [Sc/Fe], [Ti/Fe], and [V/Fe]. However, the abundance ratios have not been reproduced by numerical simulations.
Then, we perform nucleosynthesis simulations a core-collapse supernova including the neutrino process. Using the Si layer of a $13M_\odot$ zero-metal progenitor as the initial composition, we calculate the nucleosynthesis by adopting the temperature, density, neutrino flux, and duration of nucleosynthesis as arbitrary parameters and compare the results with the observed abundance ratios of Sc, Ti, and V in very-metal-poor (VMP) stars taken from the Stellar Abundances for Galactic Archaeology database.
We find that, to reproduce the abundance ratios in the VMP stars, the explosive nucleosynthesis should take place under the neutrino exposure, which is the time integration of the neutrino flux, of $\sigma_\nu\sim10^{35}\,\mathrm{erg\,cm^{−2}}$ and temperature of $2.0\,\mathrm{GK} \leq T \leq 3.2\,\mathrm{GK}$.
We also discuss whether the quantitative requirements are realized during the explosion. Although the requirements are difficult to realize in the one-dimensional simulations, the nonmonotonic thermal evolution shown in recent three-dimensional simulations may satisfy them. Because the evolution is likely caused by turbulent motion stemming from the initial asphericity of the progenitor, it is important to calculate the long-term three-dimensional supernova explosion of multidimensional metal-free progenitor models and follow the nucleosynthesis self-consistently in the future.
| Career stage | Graduate student |
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