Updated on 2025/12/15

写真a

 
AKAHO, Ryuichiro
 
Affiliation
Faculty of Science and Engineering, School of Advanced Science and Engineering
Job title
Assistant Professor(without tenure)
Degree
Doctor of Science
Homepage URL
https://sites.google.com/view/ryuichiroakaho/home

Research Experience

  • 2024.04
    -
    Now

    Waseda University   Faculty of Science and Engineering   Assistant Professor (non-tenured)

  • 2022.04
    -
    2024.03

    Japan Society for the Promotion of Science   Japan Society for the Promotion of Science (JSPS) fellowship for young scientists

Education Background

  • 2021.04
    -
    2024.03

    Waseda University   Graduate School of Advanced Science and Engineering   Department of Pure and Applied Physics, PhD program  

  • 2019.04
    -
    2021.03

    Waseda University   Graduate School of Advanced Science and Engineering   Department of Pure and Applied Physics Master's program  

  • 2015.04
    -
    2019.03

    Waseda University   Faculty of Advanced Science and Engineering   Department of Physics  

Professional Memberships

  • 2025.02
    -
    Now

    宇宙核物理連絡協議会

  • 2024.07
    -
    Now

    Japan Physical Society

  • 2022.01
    -
    Now

    理論天文学宇宙物理学懇談会

  • 2020.01
    -
    Now

    Astronomical Society of Japan

Research Areas

  • Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics

Research Interests

  • Neutron Star

  • Neutrino

  • Core-collapse Supernovae

Awards

  • Young Scientist Presentation Award, 1st place (The 2nd IReNA-Ukakuren Joint Workshop)

    2025.07   Asia Nuclear Physics Association  

  • HPCI利用研究課題優秀成果賞

    2024.10   高度情報科学技術研究機構(RIST)   高エネルギー天体現象中の量子運動論的ニュートリノ輸送シミュレーション

 

Papers

  • Neutrino Constraints on Black Hole Formation in M31

    Yudai Suwa, Ryuichiro Akaho, Yosuke Ashida, Akira Harada, Masayuki Harada, Yusuke Koshio, Masamitsu Mori, Fumi Nakanishi, Ken'ichiro Nakazato, Kohsuke Sumiyoshi, Roger A. Wendell, Masamichi Zaizen

    The Open Journal of Astrophysics    2025.11  [Refereed]

    　View Summary

    <jats:p>We investigate neutrino signals associated with black hole formation resulting from the gravitational collapse of massive stars, motivated by the candidate failed supernova M31-2014-DS1 in the Andromeda Galaxy (M31). By compiling numerical simulation results for stellar collapse, we predict the expected neutrino emission and compare these predictions with observational limits from Super-Kamiokande (SK). The simulations reveal a characteristic precursor signal consisting of a short, intense burst whose average neutrino energy rises rapidly and then ceases abruptly once the black hole forms. We examine several nuclear equations of state, specifically the Lattimer &amp; Swesty, Shen, Togashi, and SFHo models, to evaluate how the emission depends on neutron-star properties and nuclear-physics uncertainties. Comparison of the predicted event counts with SK’s non-detection of neutrinos coincident with M31-2014-DS1 already rules out part of the model space and highlights the sensitivity of current neutrino detectors to both progenitor mass and the EOS. These findings demonstrate the capability of neutrino astronomy to probe core collapse and black hole formation in failed supernova scenarios.</jats:p>

    DOI

    Scopus

  • Asymmetric emissions of neutrinos in the cooling of rotating protoneutron stars

    Laura Barrio, Kotaro Fujisawa, Ryuichiro Akaho, Hiroki Nagakura, Shoichi Yamada

    Physical Review D    2025.10  [Refereed]

    DOI

    Scopus

  • Observing Supernova Neutrino Light Curves with Super-Kamiokande. VI. A Practical Data Analysis Technique Considering Realistic Experimental Backgrounds

    Fumi Nakanishi, Ken’ichiro Nakazato, Masayuki Harada, Yusuke Koshio, Ryuichiro Akaho, Yosuke Ashida, Akira Harada, Masamitsu Mori, Kohsuke Sumiyoshi, Yudai Suwa, Roger A. Wendell, Masamichi Zaizen

    The Astrophysical Journal    2025.10  [Refereed]

    DOI

    Scopus

  • Comparative testing of subgrid models for fast neutrino flavor conversions in core-collapse supernova simulations

    Ryuichiro Akaho, Hiroki Nagakura, Shoichi Yamada

    Physical Review D    2025.08  [Refereed]

    Authorship：Lead author

    DOI

    Scopus

    3
    Citation
    (Scopus)

  • Observing Supernova Neutrino Light Curves with Super-Kamiokande. V. Distance Estimation with Neutrinos

    Yudai Suwa, Akira Harada, Masamitsu Mori, Ken’ichiro Nakazato, Ryuichiro Akaho, Masayuki Harada, Yusuke Koshio, Fumi Nakanishi, Kohsuke Sumiyoshi, Roger A. Wendell

    The Astrophysical Journal    2025.02  [Refereed]

    DOI

    Scopus

    2
    Citation
    (Scopus)

  • Quasisteady evolution of fast neutrino-flavor conversions

    Jiabao Liu, Hiroki Nagakura, Masamichi Zaizen, Lucas Johns, Ryuichiro Akaho, Shoichi Yamada

    Physical Review D    2025.01  [Refereed]

    DOI

    Scopus

    5
    Citation
    (Scopus)

  • Impacts of Black-hole-forming Supernova Explosions on the Diffuse Neutrino Background

    Ken’ichiro Nakazato, Ryuichiro Akaho, Yosuke Ashida, Takuji Tsujimoto

    The Astrophysical Journal    2024.11  [Refereed]

    DOI

    Scopus

    3
    Citation
    (Scopus)

  • Muon-induced collisional flavor instability in core-collapse supernova

    Jiabao Liu, Hiroki Nagakura, Ryuichiro Akaho, Akira Ito, Masamichi Zaizen, Shun Furusawa, Shoichi Yamada

    Physical Review D    2024.08  [Refereed]

    DOI

    Scopus

    5
    Citation
    (Scopus)

  • Physical mechanism of core-collapse supernovae that neutrinos drive

    Yamada, S., Nagakura, H., Akaho, R., Harada, A., Furusawa, S., Iwakami, W., Okawa, H., Matsufuru, H., Sumiyoshi, K.

    Proceedings of the Japan Academy. Series B, Physical and biological sciences   100 ( 3 )  2024.03  [Refereed]

    DOI

  • Collisional and fast neutrino flavor instabilities in two-dimensional core-collapse supernova simulation with Boltzmann neutrino transport

    Akaho, R., Liu, J., Nagakura, H., Zaizen, M., Yamada, S.

    Physical Review D   109 ( 2 )  2024.01  [Refereed]

    Authorship：Lead author

    DOI

    Scopus

    28
    Citation
    (Scopus)

  • Detectability of Late-time Supernova Neutrinos with Fallback Accretion onto Protoneutron Star

    Akaho, R., Nagakura, H., Foglizzo, T.

    Astrophysical Journal   960 ( 2 )  2024.01  [Refereed]

    Authorship：Lead author

    DOI

    Scopus

    6
    Citation
    (Scopus)

  • Universality of the neutrino collisional flavor instability in core-collapse supernovae

    Liu, J., Akaho, R., Ito, A., Nagakura, H., Zaizen, M., Yamada, S.

    Physical Review D   108 ( 12 )  2023.12  [Refereed]

    DOI

    Scopus

    23
    Citation
    (Scopus)

  • Protoneutron Star Convection Simulated with a New General Relativistic Boltzmann Neutrino Radiation Hydrodynamics Code

    Akaho, R., Harada, A., Nagakura, H., Iwakami, W., Okawa, H., Furusawa, S., Matsufuru, H., Sumiyoshi, K., Yamada, S.

    Astrophysical Journal   944 ( 1 )  2023.02  [Refereed]

    Authorship：Lead author

    DOI

    Scopus

    22
    Citation
    (Scopus)

  • Principal-axis Analysis of the Eddington Tensor for the Early Post-bounce Phase of Rotational Core-collapse Supernovae

    Iwakami, W., Harada, A., Nagakura, H., Akaho, R., Okawa, H., Furusawa, S., Matsufuru, H., Sumiyoshi, K., Yamada, S.

    Astrophysical Journal   933 ( 1 )  2022.07  [Refereed]

    DOI

    Scopus

    6
    Citation
    (Scopus)

  • Multidimensional Boltzmann Neutrino Transport Code in Full General Relativity for Core-collapse Simulations

    Akaho, R., Harada, A., Nagakura, H., Sumiyoshi, K., Iwakami, W., Okawa, H., Furusawa, S., Matsufuru, H., Yamada, S.

    Astrophysical Journal   909 ( 2 ) 210 - 210  2021.03  [Refereed]

    Authorship：Lead author

    DOI

    Scopus

    17
    Citation
    (Scopus)

▼display all

Presentations

  • ニュートリノ集団振動の影響を考慮したボルツマン輻射流体計算による重力崩壊型超新星シミュレーション

    日本物理学会第80回年次大会 

    Presentation date： 2025.09

  • ニュートリノ集団振動の影響を考慮したボルツマン輻射流体計算による超新星シミュレーション

    日本天文学会2025年秋季年会 

    Presentation date： 2025.09

  • Core-collapse Supernova Simulation with Subgrid Modeling of Fast Neutrino Flavor Conversion with Boltzmann Radiation Hydrodynamics Code

    SN2025gw: First IGWN Symposium on Core Collapse Supernova Gravitational Wave Theory and Detection 

    Presentation date： 2025.07

  • Core-collapse Supernova Simulation with Subgrid Modeling of Fast Neutrino Flavor Conversion

    The 2nd IReNA-Ukakuren Joint Workshop “Advancing Nuclear Astrophysics and Beyond” 

    Presentation date： 2025.07

  • 超新星の一般相対論的ボルツマン輻射流体計算

    第10回超新星ニュートリノ研究会、東京大学 

    Presentation date： 2025.03

  • Boltzmann Neutrino Radiation-hydrodynamics Simulation of Core-collapse Supernovae

    「富岳成果創出加速プログラム」基礎科学合同シンポジウム 2024 

    Presentation date： 2025.01

  • 重力崩壊型超新星爆発におけるニュートリノ集団振動の系統的調査

    日本物理学会第79回年次大会、北海道大学 

    Presentation date： 2024.09

  • 一般相対論的ボルツマン輻射流体コードによる重力崩壊型超新星爆発計算

    日本物理学会2024年秋季年会、関西学院大学 

    Presentation date： 2024.09

  • Boltzmann neutrino transport simulation of core-collapse supernovae and the collective neutrino flavor instability

    Presentation date： 2024.07

  • Boltzmann Neutrino Transport Simulation of Core-collapse Supernovae and Collective Neutrino Oscillation

     [Invited]

    iTHEMS Meeting on Quantum Information Science in Multimessenger Astrophysics 

    Presentation date： 2024.06

  • General Relativistic Boltzmann Neutrino Transport Simulation of Core-collapse Supernova

    Unraveling the History of the Universe and Matter Evolution with Underground Physics (UGAP2024), Tohoku University, Sendai, Miyagi, Japan 

    Event date：
    2024.03
    　
    　

  • 一般相対論的ボルツマン輻射流体コードによる超新星爆発計算

    第10回超新星ニュートリノ研究会、岡山大学 

    Presentation date： 2024.03

  • 三次元空間における重力崩壊型超新星のボルツマン輻射流体計算

    岩上わかな, 大川博督, 長倉洋樹, 原田了, 赤穂龍一郎, 古澤峻, 松古栄夫, 住吉光介, 山田章一

    日本天文学会年会講演予稿集 

    Presentation date： 2024

    Event date：
    2024
    　
    　

  • ボルツマン輻射流体計算で探る超新星爆発とニュートリノ集団振動

    理論天文学宇宙物理学懇談会シンポジウム、弘前大学 

    Presentation date： 2023.12

  • 超新星のボルツマン輻射輸送計算におけるニュートリノ集団振動の系統的解析

    日本天文学会 2023年秋季年会、名古屋大学 

    Presentation date： 2023.09

  • Fast and Collisional Neutrino Flavor Instabilities in Core-collapse Supernovae with Boltzmann Neutrino Transport

    Microphysics in Computational Relativistic Astrophysics (MICRA), Trento, Italy 

    Presentation date： 2023.09

  • 超新星のボルツマン輻射輸送計算におけるニュートリノ集団振動の系統的解析

    第９回超新星ニュートリノ研究会、九州大学 

    Presentation date： 2023.03

  • ボルツマン輻射輸送計算で探る超新星爆発

    第三回地下宇宙若手研究会、つくば国際会議場 

    Presentation date： 2022.11

  • Core-collapse Supernova Simulation with General Relativistic Boltzmann Neutrino Radiation-Hydrodynamics Code

    The 9th East Asian Numerical Astrophysics Meeting (EANAM9), Tenbusu Naha, Okinawa, Japan 

    Presentation date： 2022.09

  • 冷え切った原始中性子星への降着によるニュートリノ放射とその観測可能性

    日本天文学会2022秋季大会、新潟大学 

    Presentation date： 2022.09

  • 冷え切った原始中性子星への降着によるニュートリノ放射とその観測可能性

    RCNP研究会「低エネルギー核物理と高エネルギー天文学で読み解く中性子星」、大阪大学 核物理研究センター 

    Presentation date： 2022.08

  • Core-collapse Supernova Simulation with Boltzmann Neutrino Transport

     [Invited]

    Unraveling the History of the Universe and Matter Evolution with Underground Physics (UGAP2022), Tokyo University of Science, Noda, Chiba, Japan 

    Presentation date： 2022.06

  • ボルツマンニュートリノ輻射流体コードによる原始中性子星冷却計算及び今後のコード開発の展望

    第8回超新星ニュートリノ研究会、オンライン 

    Presentation date： 2022.01

  • Protoneutron Star Cooling with Boltzmann Neutrino Transport

    The 16th International Symposium on Nuclei in the Cosmos (NIC-XVI), Online 

    Event date：
    2021.09
    　
    　

  • 一般相対論的ボルツマン輻射流体計算による原子中性子星冷却

    日本天文学会2021春季大会、オンライン 

    Presentation date： 2021.03

  • 多次元一般相対論的ボルツマンニュートリノ輸送コード開発

    第7回超新星ニュートリノ研究会、オンライン 

    Presentation date： 2021.01

  • 大質量星の重力崩壊における多次元一般相対論的Boltzmannニュートリノ輸送

    第50回天文・天体物理夏の学校、オンライン 

    Presentation date： 2020.08

  • 一般相対論的ボルツマン方程式の直接解法コード開発

    日本天文学会2020春季大会 

    Presentation date： 2020.03

  • General Relativistic Boltzmann Solver for Core-collapse of Massive Stars

    The Evolution of Massive Stars and Formation of Compact Stars: from the Cradle to the Grave, Waseda University, Tokyo, Japan 

    Event date：
    2020.02
    　
    　

  • ニュートリノ輻射輸送計算のボルツマン方程式直接解法コード開発

    第一回地下宇宙若手研究会、東京大学宇宙線研究所神岡宇宙素粒子研究施設 

    Presentation date： 2020.02

  • General Relativistic Boltzmann Solver for Core-Collapse Supernovae

    CfCAユーザーズミーティング、国立天文台 

    Presentation date： 2020.01

  • 一般相対論的Boltzmann方程式の直接解法によるニュートリノ輻射輸送計算

    第49回天文・天体物理夏の学校、愛知県豊橋市 

    Presentation date： 2019.07

▼display all

Research Projects

  • The fate of massive stars explored by the first principle calculations in general relativity with nuclear physics

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2024.04
    -
    2029.03
     

  • Probe of Fundamental Physics with Numerical Study of Black Hole Formation using the Boltzmann Neutrino Transport

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2023.03
    -
    2024.03
     

Misc

  • Neutrino Oscillation Inside Core-collapse Supernovae

    Ryuichiro Akaho

    The Astronomical Herald    2025.03

    Authorship：Lead author

 

Teaching Experience

  • Science and engineering experiment 1A

    Waseda University  

    2024.04
    -
    Now
     

  • Physics Exercise B

    Waseda University  

    2024.04
    -
    Now