Papers

Also see NASA ADS

• "A Dual-Resolution Prescription in the S_N Method for Boltzmann Neutrino Transport I: Proof of Principle and the Resolution of Collision Term"
  Akira Ito, Ryuichiro Akaho, Hiroki Nagakura, Shoichi Yamada
  Submitted to the Astrophysical Journal Supplement Series, arXiv:2510.25274
  What's new: propose a new algorithm for the Boltzmann solver 
  Keywords: radiative transfer

• "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
  Submitted to The Open Journal of Astrophysics, arxiv: 2504.19510
  What's new: EOS constraint based on non-neutrino detection from BH formation event in M31 (Andromeda galaxy)
  Keywords: neutrino detection, PNS

• "Asymmetric emissions of neutrinos in the cooling of rotating proto-neutron stars"
  Laura Barrio, Kotaro Fujisawa, Ryuichiro Akaho, Hiroki Nagakura, Shoichi Yamada
  Physical Review D 112, 083039 (2025)
  What's new:  Simulating asymmetric neutrino emission from rotating PNS with Boltzmann transport
  Keywords: PNS

• "Comparative Testing of Subgrid Models for Fast Neutrino Flavor Conversions in Core-collapse Supernova Simulations"
  Ryuichiro Akaho, Hiroki Nagakura, Shoichi Yamada
  Physical Review D 112, 043015 (2025)
  What's new: First implementation of FFC subgrid model onto Boltzmann radiation-hydro code and comparison of different mixing methods
  Keywords: collective neutrino oscillation, fast flavor conversion

• "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 992 27 (2025)
  What's new:  a new backward-time analysis method for SuperK with realistic background noise taken into account
  Keywords: neutrino detection, PNS

• "Observing Supernova Neutrino Light Curves with Super-Kamiokande. V. Distance Estimation with Neutrinos Alone"
  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 980 117 (2025)
  What's new: development of the analysis method to infer CCSN distance only from neutrino signals
  Keywords: neutrino detection, PNS

• "Quasi-steady evolution of fast neutrino-flavor conversions"
  Jiabao Liu, Hiroki Nagakura, Masamichi Zaizen, Lucas Johns, Ryuichiro Akaho, Shoichi Yamada
  Physical Review D 111, 023051 (2025)
  What's new: investigated the behavior of collective neutrino flavor conversion with constantly injected neutrinos that generates persistent appearance of ELN crossing
  Keywords: fast flavor instability

• "Impacts of Black-Hole-Forming Supernova Explosions on the Diffuse Neutrino Background"
  Ken'ichiro Nakazato, Ryuichiro Akaho, Yosuke Ashida, Takuji Tsujimoto
  The Astrophysical Journal 975 71 (2024)  
  What's new: estimation of DSNB signal by taking into account the fallback emission from BH forming SNe
  Keywords: DSNB, PNS, fallback

• "Muon-induced collisional flavor instability in core-collapse supernova"
  Jiabao Liu, Hiroki Nagakura, Ryuichiro Akaho, Akira Ito, Masamichi Zaizen, Shoichi Yamada
  Physical Review D 110, 043039 (2024)
  What's new: muons can trigger the resonance-like collisional flavor instability in CCSNe
  Keywords: collisional flavor instability, muon

• "Physical mechanism of core-collapse supernovae that neutrinos drive"
  Shoichi Yamada, Hiroki Nagakura, Ryuichiro Akaho, Akira Harada, Shun Furusawa, Wakana Iwakami, Hirotada Okawa, Hideo Matsufuru, Kohsuke Sumiyoshi
  Proceedings of the Japan Academy, Series B, Physical and biological sciences 100(3) (2024)
  Review of CCSNe

• “Detectability of Late-time Supernova Neutrinos with Fallback Accretion onto Protoneutron star”
  Ryuichiro Akaho, Hiroki Nagakura, Thierry Foglizzo
  The Astrophysical Journal 960 116 (2024)
  What's new: prediction of neutrino signals due to fallback accretion onto PNS
  Keywords: PNS, fallback

• "Collisional and Fast Neutrino Flavor Instabilities in Two-dimensional Core-collapse Supernova Simulation with Boltzmann Neutrino Transport"
  Ryuichiro Akaho, Jiabao Liu, Hiroki Nagakura, Masamichi Zaizen, Shoichi Yamada
  Physical Review D 109, 023012 (2024)
  What's new: post-process analysis of collisional & fast flavor instabilities in 2D CCSN model
  Keywords: collisional flavor instability, fast flavor instability

• "Universality of the Neutrino Collisional Flavor Instability in Core Collapse Supernovae"
  Jiabao Liu, Ryuichiro Akaho, Akira Ito, Hiroki Nagakura, Masamichi Zaizen, Shoichi Yamada
  Physical Review D 108, 123024 (2023)
  What's new: post-process analysis of collisional flavor instability in 1D CCSN models
  Keywords: collisional flavor instability

• “Protoneutron Star Convection Simulated with a New General Relativistic Boltzmann Neutrino Radiation-Hydrodynamics Code”
  Ryuichiro Akaho, Akira Harada, Hiroki Nagakura, Wakana Iwakami, Hirotada Okawa, Shun Furusawa, Hideo Matsufuru, Kohsuke Sumiyoshi, and Shoichi Yamada
  The Astrophysical Journal 944 60 (2023)
  What's new: development of GR Boltzmann+hydro solver and application to PNS convection
  Keywords: Botzmann radiation-hydrodynamics, GR, PNS 

• “Principal-Axis Analysis of the Eddington Tensor for the Early Post-Bounce Phase of Rotational Core-Collapse Supernovae”
  Wakana Iwakami, Akira Harada, Hiroki Nagakura, Ryuichiro Akaho, Hirotada Okawa, Shun Furusawa, Hideo Matsufuru, Kohsuke Sumiyoshi, and Shoichi Yamada
  The Astrophysical Journal 933 91 (2022)
  What's new:  verifications of  moment closures in rotating CCSN
  Keywords: Botzmann transport, moment method

• "Multidimensional Boltzmann Neutrino Transport Code in Full General Relativity for Core-collapse Simulations"
  Ryuichiro Akaho, Akira Harada, Hiroki Nagakura, Kohsuke Sumiyoshi, Wakana Iwakami, Hirotada Okawa, Shun Furusawa, Hideo Matsufuru, and Shoichi Yamada
  The Astrophysical Journal 909 210 (2021)
  What's new: development of GR Boltzmann solver
  Keywords: Botzmann transport, GR