KEIO RESEARCHERS INFORMATION SYSTEM

Career 【 Display / hide 】

Career 【 Display / hide 】

• 2021.04

  -

  2023.03

  福岡大学, 爆発天体研究所, ポスト・ドクター

• 2023.04

  -

  2025.09

  国立天文台, 科学研究部, 日本学術振興会特別研究員-PD

Academic Background 【 Display / hide 】

Academic Background 【 Display / hide 】

• 2018.04

  -

  2021.03

  The University of Tokyo, Graduate School of Science, Department of Astronomy

  Graduate School, Completed, Doctoral course

Academic Degrees 【 Display / hide 】

Academic Degrees 【 Display / hide 】

• 博士(理学), The University of Tokyo, Coursework, 2021.03

Research Areas 【 Display / hide 】

Research Areas 【 Display / hide 】

• Natural Science / Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics (Particle astrophysics)

Books 【 Display / hide 】

Books 【 Display / hide 】

• Alpha-clustering Structure of the Light Nuclei and its Impact on Astrophysics and Cosmology

  Kajino T., Yao X., He Z., Kusakabe M., Yamazaki Y., Luo Y., Mori K., Akito Arima Memorial Volume, 2025.01

  　View Summary

  Alpha-clustering structure of the light nuclei 7Be and 7Li and their radiative α-capture reactions play the significant roles in nucleosynthesis of various astrophysical phenomena. We discuss their roles in the missing solar neutrinos, Big-Bang nucleosynthesis, explosive r-process in supernovae, collapsars and binary neutron star mergers, Galactic chemical evolution, neutrino flavor oscillations, and extremely enhanced lithium abundance in red clump stars. We summarize the impact on various astrophysical and cosmological problems.

  • Access to Document (DOI)

Papers 【 Display / hide 】

Papers 【 Display / hide 】

• Impacts of axion cooling on the direct detection of supernova axions

  Mori K., Mori M.

  Journal of Cosmology and Astroparticle Physics 2025 ( 11 )  2025.11

  　View Summary

  Core-collapse supernovae provide a unique opportunity to probe axions because they can be a copious source of the particles. It has recently been proposed that axion helioscopes can be used for the direct search for supernova axions if a supernova event appears within a few hundred parsecs. However, the event number of supernova axions has been estimated only within the post-process framework. In this study, we perform long-term supernova simulations for a 9.6M<inf>⊙</inf>star coupled with the axion emission to reevaluate the event number of axions detected by the helioscopes. We find that the additional cooling induced by the axion emission can significantly decrease the temperature in the proto-neutron star. As a result, the axion luminosity and hence the axion event number are reduced, compared with the result obtained through post-processing. Our result indicates that the nonlinear feedback of the axion emission is an essential factor to predict the axion detectability, and underscores the need for systematic simulation studies across various progenitor models.

  • Access to Document (DOI)

• Progenitor dependence of neutrino-driven supernova explosions with the aid of heavy axionlike particles

  Takata T., Mori K., Nakamura K., Kotake K.

  Physical Review D 111 ( 10 )  2025.05

  ISSN  24700010

  　View Summary

  We perform spherically symmetric simulations of core-collapse supernovae with the aid of heavy axionlike particles (ALPs) which interact with photons and redistribute energy within supernova matter. We explore a wide ALP parameter space that includes MeV-scale ALP mass ma and the ALP-photon coupling constant gaγ∼10-10 GeV-1, employing three progenitor models with zero-age main-sequence mass of 11.2M⊙, 20.0M⊙, and 25.0M⊙. We find a general trend that, given ma 300 MeV, heavier ALPs are favorable for the shock wave to be successfully revived, aiding the onset of the neutrino-driven explosion. However, if ALPs are heavier than ∼400 MeV, the explosion is failed or weaker than that for the models with smaller ma, because of an insufficient temperature inside the supernova core to produce heavy ALPs. The maximum temperature in the core depends on the initial progenitor structure. Our simulations indicate that the high-temperature environment in the collapsing core of massive progenitors leads to a significant impact of ALPs on the explodability.

  • Access to Document (DOI)

• Core-collapse supernova explosions hindered by eV-mass sterile neutrinos

  Mori K., Takiwaki T., Kohri K., Nagakura H.

  Physical Review D 111 ( 8 )  2025.04

  ISSN  24700010

  　View Summary

  Light sterile neutrinos, νs, are often introduced to explain an anomalous deficit in the electron antineutrino flux from nuclear reactors. If they exist, sterile neutrinos would also be produced in collapsing massive stars through the active-sterile neutrino oscillation. In order to investigate the impacts of sterile neutrinos on supernova dynamics, we perform two-dimensional neutrino-radiation hydrodynamic simulations of stellar core-collapse coupled with the active-sterile oscillation through the Mikheyev-Smirnov-Wolfenstein effect. As the initial condition of our simulations, we adopt a blue supergiant model that is tuned to reproduce observational features of the SN 1987A progenitor to compare our models with observations of the event. It is found that the active-sterile oscillation reduces the νe and ν¯e fluxes and decreases the explosion energy. We also find that, if the mixing angle θ and the mass difference δms2 between νe and νs are large enough, the star fails to explode. This suggests that these mixing parameters relevant to sterile neutrinos could be constrained by supernova explodability, though other uncertainties in supernova theory need to be addressed to refine them. In addition, we predict neutrino signals from a nearby supernova event and find that the neutrino event number can significantly decrease because the νe and ν¯e fluxes are reduced. In particular, DUNE observations of νe will be useful to search for a signature of sterile neutrinos with a tiny mixing angle because a smaller mixing angle leads to a larger effect on the νe flux.

  • Access to Document (DOI)

• Three-dimensional core-collapse supernova models with phenomenological treatment of neutrino flavor conversions

  Mori K., Takiwaki T., Kotake K., Horiuchi S.

  Publications of the Astronomical Society of Japan 77 ( 2 ) L9 - L15 2025.04

  ISSN  00046264

  　View Summary

  We perform three-dimensional supernova simulations with a phenomenological treatment of neutrino flavor conversions. We show that the explosion energy can increase to as high as ∼ 10⁵¹ erg depending on the critical density for the onset of flavor conversions, due to a significant enhancement of the mean energy of electron antineutrinos. Our results confirm previous studies showing such energetic explosions, but for the first time in three-dimensional configurations. In addition, we predict neutrino and gravitational wave (GW) signals from a nearby supernova explosion aided by flavor conversions. We find that the neutrino event number decreases because of the reduced flux of heavy-lepton neutrinos. In order to detect GWs, next-generation GW telescopes such as Cosmic Explorer and the Einstein Telescope are needed even if the supernova event is located at the Galactic Center. These findings show that the neutrino flavor conversions can significantly change supernova dynamics and highlight the importance of further studies on the quantum kinetic equations to determine the conditions of the conversions and their asymptotic states.

  • Access to Document (DOI)

• Two-dimensional models of core-collapse supernova explosions assisted by heavy sterile neutrinos

  Mori K., Takiwaki T., Kotake K., Horiuchi S.

  Physical Review D 110 ( 2 )  2024.07

  ISSN  24700010

  　View Summary

  Core-collapse supernovae can be a copious source of sterile neutrinos, hypothetical particles that mix with active neutrinos. We develop two-dimensional stellar core-collapse models that incorporate the mixing between tau neutrinos and heavy sterile neutrinos - those with the mass of 150-200 MeV - to investigate signatures of sterile neutrinos in supernova observables. We find that the decay channel of a sterile neutrino into a pion and a tau neutrino can enhance the explosion energy and the synthesized nickel mass. Although the inclusion of sterile neutrinos considered in this study slightly reduce the neutrino and gravitational-wave signals, we find that they are still detectable for a Galactic event. Furthermore, we point out that if sterile neutrinos are as massive as ∼200 MeV, they produce high-energy tau antineutrinos with energies of ∼80 MeV, the detection of which can be a smoking signature of the sterile neutrinos and where Hyper-Kamiokande should play a pivotal role.

  • Access to Document (DOI)

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Reviews, Commentaries, etc. 【 Display / hide 】

Reviews, Commentaries, etc. 【 Display / hide 】

• 超新星シミュレーションを活かした素粒子標準模型を超えた物理の探索

  森　寛治

  天文月報 119   455 2026.07

  Article, review, commentary, editorial, etc. (other), Single Work, Lead author, Last author, Corresponding author

Research Projects of Competitive Funds, etc. 【 Display / hide 】

Research Projects of Competitive Funds, etc. 【 Display / hide 】

• Exploring Sterile Neutrinos with Multi-dimensional Supernova Simulations

  2025.04

  -

  2027.03

  学術変革領域研究(A), Principal investigator

• Theoretical Investigation of Multi-messenger Signals of Axion-like Particles in Core-collapse Supernovae

  2023.04

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  2026.03

  若手研究, Principal investigator

Awards 【 Display / hide 】

Awards 【 Display / hide 】

• 宇宙核物理連絡協議会若手奨励賞

  森　寛治, 2025.03, 宇宙核物理連絡協議会

  Type of Award： Award from Japanese society, conference, symposium, etc.

Courses Previously Taught 【 Display / hide 】

Courses Previously Taught 【 Display / hide 】

• 宇宙科学入門

  駒澤大学

  2025.04

  -

  Present

  , 

  Spring Semester, Undergraduate (liberal arts), Lecture, Within own ｆaculty

• 現代の宇宙像

  駒澤大学

  2025.04

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  Present

  , 

  Autumn Semester, Undergraduate (liberal arts), Lecture, Within own ｆaculty