中性子星合体におけるrプロセス元素合成と重力波対応天体

• Project/Area Number: 26400237
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Astronomy
• Research Institution: Sophia University (2015-2018); The Institute of Physical and Chemical Research (2014)
• Principal Investigator: 和南城 伸也 上智大学, 理工学部, 准教授 (30327879)
• Co-Investigator(Kenkyū-buntansha): 関口 雄一郎 東邦大学, 理学部, 准教授 (50531779) ; 石丸 友里 国際基督教大学, 教養学部, 上級准教授 (90397068)
• Project Period (FY): 2014-04-01 – 2019-03-31
• Project Status: Discontinued (Fiscal Year 2018)
• Budget Amount: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2018: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2017: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2016: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2015: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000); Fiscal Year 2014: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: 中性子星合体 / 超新星爆発 / rプロセス / 重力波 / キロノバ / 銀河化学進化 / 矮小銀河 / 重力波対応天体 / 原子核反応 / 元素合成 / 中性子星 / 状態方程式 / 電子捕獲 / ニュートリノ / 銀河系 / 化学進化

Outline of Annual Research Achievements

本研究の目的は、中性子星合体における元素合成および重力波対応天体キロノバの研究により、レアアース、金、ウランなどのrプロセス元素の起源を解明することであった。中性子星合体の元素合成の計算 (Wanajo et al. 2014) に基づくキロノバの観測予測を行い (Tanaka et al. 2018)、その直後に中性子星合体GW170817が発見された。対応するキロノバの観測結果は我々の予測の範囲内で説明され、rプロセス元素がつくられたことが示された。
中性子星合体には1億年以上を要するため、銀河初期の星に観測されるrプロセス元素の存在が説明できないという問題があった。銀河系は様々な質量のサブハローの合体により形成され、低質量のサブハローほど星形成率が低いという仮説の基に銀河化学進化の計算を行い、観測されるrプロセス元素の存在は中性子星合体で説明できること、ストロンチウムなどの軽いrプロセス元素には超新星などの別も起源も必要なこと、そしてサブハローモデルが矮小銀河の化学進化も説明可能であることを明らかにした (Ishimaru et al. 2015; Ojima et al. 2018)。
最終年度（本年度）は、中性子星合体がrプロセス元素の主要な起源であることを実証するために、rプロセス元素の核崩壊加熱率に関する研究を行った (Wanajo 2018)。中性子星合体GW170817の観測によりレアアースが存在することは明らかにされたが、金やウランなどの重いrプロセス元素がつくられた証拠は得られていない。GW170817での主要な熱源はrプロセス元素ではなくニッケル66（半減期2.3日）のような軽い元素であった可能性を示し、重いrプロセス元素がつくられたことを明らかにするには、将来の観測でカリフォルニウム254（半減期61日）の兆候を捉えることが有効であることを示した。

Research Products

• [Int'l Joint Research] パリ天体物理学研究所/パリ天文台(フランス)
• [Int'l Joint Research] マックスプランク研究所/GSI(ドイツ)
• [Int'l Joint Research] モナッシュ大学(オーストラリア)
• [Int'l Joint Research] パリ天体物理学研究所/パリ天文台(フランス)
• [Int'l Joint Research] マックスプランク研究所(ドイツ)
• [Int'l Joint Research] モナッシュ大学(オーストラリア)
• [Int'l Joint Research] パリ天体物理学研究所/パリ天文台(フランス)
• [Int'l Joint Research] マックスプランク研究所(ドイツ)
• [Int'l Joint Research] クイーンズ大学ベルファスト(英国)
• [Int'l Joint Research] モナッシュ大学(オーストラリア)
• [Journal Article] Mass measurements of neutron-deficient Y, Zr, and Nb isotopes and their impact on rp and νp nucleosynthesis processes (2018)
  • Author(s): Y.M. Xing, K.A. Li, Y.H. Zhang, X.H. Zhou, M. Wang, Yu.A. Litvinov, K. Blaum, S. Wanajo, S. Kubono, G. Martinez-Pinedo, et al.
  • Journal Title: Phys. Lett. B Volume: 781 Pages: 358-363
  • DOI: 10.1016/j.physletb.2018.04.009
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Chemical analysis of very metal-poor turn-off stars from SDSS-DR12 (2018)
  • Author(s): Francois, P., Caffau, E., Wanajo, S., Aguado, D., Spite, M., Aoki, M., Aoki, W., Bonifacio, P., Gallagher, A. J., Salvadori, S., Spite, F.
  • Journal Title: Astronomy & Astrophysics Volume: 619 Pages: A10-A10
  • DOI: 10.1051/0004-6361/201833824
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Stochastic Chemical Evolution of Galactic Subhalos and the Origin of r-process Elements (2018)
  • Author(s): Ojima Takuya、Ishimaru Yuhri、Wanajo Shinya、Prantzos Nikos、Francois Patrik
  • Journal Title: The Astrophysical Journal Volume: 865 Issue: 2 Pages: 87-87
  • DOI: 10.3847/1538-4357/aada11
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Physical conditions for the r-process I. radioactive energy sources of kilonovae (2018)
  • Author(s): Wanajo, S.
  • Journal Title: The Astrophysical Journal Volume: in press
  • Peer Reviewed / Open Access
• [Journal Article] Nucleosynthesis in the Innermost Ejecta of Neutrino-Driven Supernova Explosions in Two Dimensions (2018)
  • Author(s): Wanajo, S., Mueller, B., Janka, H.-T., Heger, A.
  • Journal Title: The Astrophysical Journal Volume: 852 Issue: 1 Pages: 40-20
  • DOI: 10.3847/1538-4357/aa9d97
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Properties of Kilonovae from Dynamical and Post-Merger Ejecta of Neutron Star Mergers (2018)
  • Author(s): Tanaka, M., Kato, D., Gaigalas, G., Rynkun, P., Radziute, L., Wanajo, S., Sekiguchi, Y., Nakamura, N., Tanuma, H., Murakami, I., Sakaue, H. A.
  • Journal Title: The Astrophysical Journal Volume: 852 Issue: 2 Pages: 109-109
  • DOI: 10.3847/1538-4357/aaa0cb
  • NAID: 120007180031
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Enrichment of Zinc in Galactic Chemodynamical Evolution Models (2018)
  • Author(s): Hirai, Y., Saitoh, T. R., Ishimaru, Y., Wanajo, S.
  • Journal Title: The Astrophysical Journal Volume: 855 Issue: 1 Pages: 63-63
  • DOI: 10.3847/1538-4357/aaaabc
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Simulations of Electron Capture and Low-Mass Iron Core Supernovae (2017)
  • Author(s): Mueller, B., Wanajo, S., Janka, H.-Th., Heger, A., Gay, D., Sim, S. A.
  • Journal Title: Memorie della Societa Astronomica Italiana Volume: 88 Pages: 288-293
  • Open Access / Int'l Joint Research
• [Journal Article] Stochastic Chemical Evolution of Sub-Halos and the Origin of R-Process Elements (2017)
  • Author(s): Ojima, T., Ishimaru, Y., Wanajo, S., Prantzos, N.
  • Journal Title: Proceedings of the 14th International Symposium on Nuclei in the Cosmos, JPS Conf. Proc. Volume: 14 Pages: 020208-3
  • DOI: 10.7566/jpscp.14.020208
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Enrichment of R-Process Elements by Neutron Star Mergers Through the Sub-Halo Clustering (2017)
  • Author(s): Ishimaru, Y., Ojima, T., Wanajo, S., Prantzos, N.
  • Journal Title: Proceedings of the 14th International Symposium on Nuclei in the Cosmos, JPS Conf. Proc. Volume: 14 Pages: 020210-3
  • DOI: 10.7566/jpscp.14.020210
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Abundance of Weak r-process Elements of Metal-Poor Stars ~Universality or Diversity?~ (2017)
  • Author(s): Aoki, M., Ishimaru, Y., Aoki, W., Wanajo, S.
  • Journal Title: Proceedings of the 14th International Symposium on Nuclei in the Cosmos, JPS Conf. Proc. Volume: 14 Pages: 020302-3
  • DOI: 10.7566/jpscp.14.020302
  • Peer Reviewed / Open Access
• [Journal Article] Diversity of Abundance Patterns of Light Neutron-capture Elements in Very-metal-poor Stars (2017)
  • Author(s): Misa Aoki, Yuhri Ishimaru, Wako Aoki, Shinya Wanajo
  • Journal Title: The Astrophysical Journal Volume: 837 Issue: 1 Pages: 8-16
  • DOI: 10.3847/1538-4357/aa5d08
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Production and Distribution of 44Ti and 56Ni in a Three-Dimensional Supernova Model Resembling Cassiopeia A (2017)
  • Author(s): Wongwathanarat, A., Janka, H.-T., Mueller, E., Pllumbi, E., Wanajo, S.
  • Journal Title: The Astrophysical Journal Volume: 842 Issue: 1 Pages: 13-20
  • DOI: 10.3847/1538-4357/aa72de
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Radioactive decay products in neutron star merger ejecta: heating efficiency and γ-ray emission (2016)
  • Author(s): Hotokezaka, K., Wanajo, S., Tanaka, M., Bamba, A., Terada, Y., Piran, T.
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 459 Issue: 1 Pages: 35-43
  • DOI: 10.1093/mnras/stw404
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] The r-process in black hole-neutron star mergers based on a fully general-relativistic simulation (2016)
  • Author(s): Nishimura, N.; Wanajo, S.; Sekiguchi, Y.; Kiuchi, K.; Kyutoku, K.; Shibata, M.
  • Journal Title: Journal of Physics: Conference Series Volume: 665 Pages: 012059-012059
  • DOI: 10.1088/1742-6596/665/1/012059
  • Acknowledgement Compliant
• [Journal Article] HST/STIS abundances in the uranium rich metal poor star CS 31082-001: Constraints on the r-Process (2016)
  • Author(s): Siqueira-Mello, C.; Spite, M.; Barbuy, B.; Spite, F.; Caffau, E.; Hill, V.; Wanajo, S.; Primas, F.; Plez, B.; Cayrel, R.; Andersen, J.; Nordstroem, B.; Sneden, C.; Beers, T. C.; Bonifacio, P.; Francois, P.; Molaro, P.
  • Journal Title: Journal of Physics: Conference Series Volume: 665 Pages: 012056-012056
  • DOI: 10.1088/1742-6596/665/1/012056
  • Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Neutron Star Mergers as the Origin of r-Process Elements in the Galactic Halo Based on the Sub-halo Clustering Scenario (2015)
  • Author(s): 石丸 友里, 和南城 伸也, Nikos Prantzos
  • Journal Title: The Astrophysical Journal Letters Volume: 804 Issue: 2 Pages: L35-L35
  • DOI: 10.1088/2041-8205/804/2/l35
  • Peer Reviewed / Open Access
• [Journal Article] IMPACT OF NEUTRINO FLAVOR OSCILLATIONS ON THE NEUTRINO-DRIVEN WIND NUCLEOSYNTHESIS OF AN ELECTRON-CAPTURE SUPERNOVA (2015)
  • Author(s): Else Pllumbi , Irene Tamborra , Shinya Wanajo , Hans-Thomas Janka , and Lorenz Huedepohl
  • Journal Title: Astrophysical Journal Volume: 808 Issue: 2 Pages: 188-188
  • DOI: 10.1088/0004-637x/808/2/188
  • Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Production of all the r-process nuclides in the dynamical ejecta of neutron star mergers (2014)
  • Author(s): S. Wanajo, Y. Sekiguchi, N. Nishimura, K. Kiuchi, K. Kyutoku, and M. Shibata,
  • Journal Title: Astrophysical Journal Letters Volume: 789 Issue: 2 Pages: L39-L39
  • DOI: 10.1088/2041-8205/789/2/l39
  • Peer Reviewed / Acknowledgement Compliant
• [Presentation] rプロセスと核崩壊加熱率 (2018)
  • Author(s): 和南城伸也
  • Organizer: 重力波観測時代のrプロセスと不安定核
  • Invited
• [Presentation] rプロセスと核分裂 (2018)
  • Author(s): 和南城伸也
  • Organizer: 超重元素研究の新展開
  • Invited
• [Presentation] The r-process in neutron star mergers and the radioactive energies (2018)
  • Author(s): Wanajo, S.
  • Organizer: Fifth Joint Meeting of the Nuclear Physics Divisions of the APS and The JPS
  • Int'l Joint Research / Invited
• [Presentation] r-Process in Supernovae and Neutron Star Mergers (2017)
  • Author(s): 和南城伸也
  • Organizer: The Japan-France Workshop “Neutron Star Mergers and Galactic Chemical Evolution”
  • Int'l Joint Research
• [Presentation] Galactic Chemical Evolution of r-Process Elements (2017)
  • Author(s): 石丸友里
  • Organizer: The Japan-France Workshop “Neutron Star Mergers and Galactic Chemical Evolution”
  • Int'l Joint Research
• [Presentation] r-Process Nucleosynthesis in Neutron Star Mergers (2017)
  • Author(s): 和南城伸也
  • Organizer: Stellar Evolution, Supernova and Nucleosynthesis Across Cosmic Time
  • Int'l Joint Research / Invited
• [Presentation] Nucleosynthesis in Neutron Star Mergers (2017)
  • Author(s): 和南城伸也
  • Organizer: Ito International Research Center (IIRC) Symposium “Perspectives of the Physics of Nuclear Structure”
  • Int'l Joint Research / Invited
• [Presentation] 重元素の起源 (2017)
  • Author(s): 和南城伸也
  • Organizer: 第30回理論懇シンポジウム「星の物理の新地平」
  • Invited
• [Presentation] r-Process in Neutron Star Mergers and Kilonova Emission (2017)
  • Author(s): 和南城伸也
  • Organizer: The first annual symposium of the innovative area "Gravitational Wave Physics and Astronomy: Genesis"
  • Int'l Joint Research / Invited
• [Presentation] Compact binary mergers as the origins of r-process elements (2016)
  • Author(s): Wanajo, Shinya
  • Organizer: Nuclear Physics, Compact Stars, and Compact Star Mergers 2016
  • Place of Presentation: Yukawa Institute for Theoretical Physics, Kyoto, Japan
  • Year and Date: 2016-10-17
  • Int'l Joint Research / Invited
• [Presentation] Origin of r-process elements and nuclear cosmo-chronology (2016)
  • Author(s): Wanajo, Shinya
  • Organizer: The Milky Way and its environment: gaining insights into the drivers of galaxy formation and evolution
  • Place of Presentation: Institut d'Astrophysique de Paris, Paris, France
  • Year and Date: 2016-09-19
  • Int'l Joint Research
• [Presentation] The r-process in the ejecta of neutron star mergers (2016)
  • Author(s): Wanajo, Shinya
  • Organizer: 14th International Symposium on Nuclei in the Cosmos XIV
  • Place of Presentation: Toki Messe, Niigata, Japan
  • Year and Date: 2016-06-19
  • Int'l Joint Research / Invited
• [Presentation] Nucleosynthesis with multi-dimensional supernova models (2016)
  • Author(s): Wanajo, Shinya
  • Organizer: The r- process nucleosynthesis: connecting FRIB with the cosmos
  • Place of Presentation: Michigan State University, Lansing, USA
  • Year and Date: 2016-05-31
  • Int'l Joint Research / Invited
• [Presentation] The r-process in the ejecta of neutron star mergers (2015)
  • Author(s): Shinya Wanajo
  • Organizer: Symposium on ‘Quarks to Universe in Computational Science
  • Place of Presentation: 奈良春日野国際フォーラム（奈良県・奈良市）
  • Year and Date: 2015-11-04
  • Int'l Joint Research / Invited
• [Presentation] The r-process and electromagnetic emission from neutron star mergers (2015)
  • Author(s): Shinya Wanajo
  • Organizer: GRB Workshop 2015
  • Place of Presentation: 理化学研究所（埼玉県・和光市）
  • Year and Date: 2015-08-31
  • Int'l Joint Research / Invited
• [Presentation] Nucleosynthesis of r-process elements in the ejecta from supernovae and neutron star mergers (2015)
  • Author(s): Shinya Wanajo
  • Organizer: First stars, galaxies, and black holes: Now and Then
  • Place of Presentation: University of Groningen (Groningen, Netherlands)
  • Year and Date: 2015-06-15
  • Int'l Joint Research
• [Presentation] Nucleosynthesis with multi-dimensional supernova models (2015)
  • Author(s): Shinya Wanajo
  • Organizer: F.O.E. Fifty-One Erg
  • Place of Presentation: North Carolina State University (Raleigh, USA)
  • Year and Date: 2015-06-01
  • Int'l Joint Research / Invited
• [Presentation] 超新星ニュートリノ加熱物質中の元素合成 (2015)
  • Author(s): 和南城伸也
  • Organizer: 宇宙の歴史をひもとく地下素粒子原子核研究
  • Place of Presentation: 神戸大学（兵庫県・神戸市）
  • Year and Date: 2015-05-15
  • Invited
• [Presentation] Universality of the r-process (2015)
  • Author(s): Shinya Wanajo
  • Organizer: 12th Russbach School on Nuclear Astrophysics
  • Place of Presentation: Hotel Gasthof Auswinkl, Russbach, Austria
  • Year and Date: 2015-03-08 – 2015-03-14
  • Invited
• [Presentation] r-process 元素合成 (2015)
  • Author(s): 和南城伸也
  • Organizer: コンパクト連星合体からの重力波・電磁波放射と その周辺領域
  • Place of Presentation: 京都大学基礎物理学研究所（京都府京都市左京区）
  • Year and Date: 2015-02-12 – 2015-02-14
  • Invited
• [Presentation] Origin of the r-process nuclei and there levant nuclear physics (2014)
  • Author(s): Shinya Wanajo
  • Organizer: Progress in nuclear shell-model calculations in CNS-RIKEN collaboration
  • Place of Presentation: 理化学研究所（埼玉県和光市）
  • Year and Date: 2014-11-26 – 2014-11-28
  • Invited
• [Presentation] The r-process in the ejecta from neutron star mergers (2014)
  • Author(s): Shinya Wanajo
  • Organizer: Recent progress on r-process and nucleosynthesis
  • Place of Presentation: 理化学研究所（埼玉県和光市）
  • Year and Date: 2014-11-25
  • Invited
• [Presentation] Origin of gold: supernovae vs neutron star mergers (2014)
  • Author(s): Shinya Wanajo
  • Organizer: Kavli IPMU - RIKEN iTHES - Osaka TSRP Symposium ”Frontiers of Theoretical Science MATTER, LIFE and COSMOS - ”
  • Place of Presentation: Kavli IPMU（千葉県柏市）
  • Year and Date: 2014-11-06
  • Invited
• [Presentation] r-process in the neutrino-processed ejecta of neutron star mergers (2014)
  • Author(s): Shinya Wanajo
  • Organizer: 4th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
  • Place of Presentation: Hilton Waikoloa Villagel, Hawaii, USA
  • Year and Date: 2014-10-07 – 2014-10-11
  • Invited
• [Presentation] origin of the r-process nuclei (2014)
  • Author(s): Shinya Wanajo
  • Organizer: Advances and perspectives in computational nuclear physics
  • Place of Presentation: Hilton Waikoloa Village, Hawaii, USA
  • Year and Date: 2014-10-05 – 2014-10-07
  • Invited
• [Presentation] r-process in neutron star mergers (2014)
  • Author(s): 和南城伸也
  • Organizer: 新学術領域研究「実験と観測で解き明かす中性子星の核物質」第 3 回研究会
  • Place of Presentation: 熱川ハイツ（静岡県賀茂郡東伊豆町）
  • Year and Date: 2014-09-23 – 2014-09-25
  • Invited
• [Presentation] r-process in neutron star mergers (2014)
  • Author(s): Shinya Wanajo
  • Organizer: Nuclear Physics and Astrophysics of Neutron-Star Mergers and Supernovae
  • Place of Presentation: ECT*, Trento, Italy
  • Year and Date: 2014-09-08 – 2014-09-12
  • Invited
• [Presentation] r-process in neutron star mergers (2014)
  • Author(s): 和南城伸也
  • Organizer: Supernovae and gamma-ray bursts
  • Place of Presentation: 理化学研究所（埼玉県和光市）
  • Year and Date: 2014-08-25 – 2014-08-27
  • Invited
• [Presentation] 中性子星合体のrプロセス (2014)
  • Author(s): 和南城伸也
  • Organizer: 「宇宙核物理実験の現状と将来」研究会
  • Place of Presentation: 大阪大学核物理研究センター（大阪府茨木市）
  • Year and Date: 2014-08-07 – 2014-08-08
  • Invited
• [Presentation] r-process in neutron star mergers (2014)
  • Author(s): Shinya Wanajo
  • Organizer: iTHES-Kavli IPMU-RESCEU Joint Meeting
  • Place of Presentation: 理化学研究所（埼玉県和光市）
  • Year and Date: 2014-07-07 – 2014-07-08
  • Invited
• [Presentation] r-process in SN and neutron star mergers (2014)
  • Author(s): Shinya Wanajo
  • Organizer: Simulating the Supernova Neutrinosphere with Heavy Ion Collisions
  • Place of Presentation: ECT*, Trento, Italy
  • Year and Date: 2014-04-07 – 2014-04-11
  • Invited
• [Remarks] 金やウランなどの重い元素は中性子星の合体で作られた可能性が高い
  • URL: http://www.riken.jp/pr/press/2014/20140717_2/
• [Remarks] 金やウランなど鉄より重い元素は 中性子星の合体によってつくられた!?
  • URL: http://www.riken.jp/~/media/riken/pr/publications/news/2014/rn201411.pdf