Elucidating neutrino oscillations and mass hierarchy in supernova nucleosynthesis

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K03958
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 15010:Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: National Astronomical Observatory of Japan
• Principal Investigator: Kajino Toshitaka 国立天文台, 科学研究部, 特別客員研究員 (20169444)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 元素合成 / 銀河化学進化 / 超新星 / ニュートリノ振動

Outline of Final Research Achievements

Heavy elements in the solar system are thought to originate from γ-process (p-process), s-process, r-process, ν-process and νp-process. We elucidated that the previously unresolved p-nuclei of Mo and Ru originate from the νp process in hypernovae by clarifying the roles of deexcitation of the Hoyle resonance state in carbon-12. We conclude that about 90% of the solar r-process elements are produced in collapsars and magneto-rotationally driven supernovae, while the remaining 10% are produced in binary neutron star mergers in recent epoch of cosmic evolution. Our galactic chemical evolution model reveals that the former two contributions are dominant over the entire cosmic history. It was found that the i- and s-processes follow the collapsar r-process due to the abundant neutrons produced by the fission of transuranium elements in the collapsar r-process, resulting in strong even-odd dependence near A = 150 mass abundance pattern of rare elements.

Free Research Field

天体核物理、宇宙論、原子核物理

Academic Significance and Societal Importance of the Research Achievements

p核元素群でアイソトープ比が異常に高いMoとRuの起源は、Burbidge-Burbidge-Fowler-Hoyle(1957)の研究以来、未解明であった。極超新星でニュートリノ振動と原子核相互作用が重要な役割を果たすνp過程が起源であることと、炭素12のホイル共鳴状態の脱励起の役割を解明したことは、宇宙核物理、ニュートリノ物理、および核物理学にインパクトを与える。中性子星連星系合体がｒ過程元素の主要な起源天体でないことを示し、重力波天体と銀河化学進化の研究にインパクトを与える。コラプサーでr過程、i過程、ｓ過程が共存しうることは、太陽系重元素の起源論の解釈に変更を迫る可能性がある。