40 citations · 181 across the 18 of their papers we have counts for
19 papers
A Diagnostic Method for Proto-Neutron Star Magnetic Fields by Supernova Fallback Neutrinos
Akihiro Inoue, Yudai Suwa, Ryuichiro Akaho +3
Young isolated neutron stars exhibit a wide range of magnetic field strengths. To understand the origin of this diversity, it is important to observationally constrain magnetic fie…
Momentum Space Resolution Dependence in Boltzmann Neutrino Radiation Hydrodynamics Simulations of Core-collapse Supernovae
Ryuichiro Akaho
Finite momentum space resolution is a primary source of uncertainty in solving the Boltzmann equation with the discrete-ordinates method. In this paper, the momentum space resoluti…
Numerical Studies of Accretion Flows onto a Neutron Star Engulfed in a Massive Star
Daiyu Sakurai, Ryuichiro Akaho, Shoichi Yamada
Massive stars commonly form binaries that can evolve into compact systems via common envelope evolution (CEE), a critical but poorly understood phase -- especially when the compani…
Comprehensive neutrino light curves and spectra: from pre-supernova evolution to early supernova phase
Chinami Kato, Hiroki Nagakura, Akira Ito +4
We present the first systematic study of neutrino emissions from massive stars, continuously tracking the late evolutionary stages through the early core-collapse supernova phase.…
Bifurcated Impact of Neutrino Fast Flavor Conversion on Core-collapse Supernovae Informed by Multi-angle Neutrino Radiation Hydrodynamics
Ryuichiro Akaho, Hiroki Nagakura, Wakana Iwakami +6
In this {\it Letter}, we present a compelling and robust argument for the roles of neutrino fast flavor conversion (FFC) in the explosion mechanism of core-collapse supernova (CCSN…
A Dual-Resolution Prescription in the Method for Boltzmann Neutrino Transport I: Proof of Principle and the Resolution of Collision Term
Akira Ito, Ryuichiro Akaho, Hiroki Nagakura +1
We propose a dual-resolution prescription meant for the Boltzmann neutrino transport, in which the advection and collision terms are calculated with different angular resolutions i…
Comparative Testing of Subgrid Models for Fast Neutrino Flavor Conversions in Core-collapse Supernova Simulations
Ryuichiro Akaho, Hiroki Nagakura, Shoichi Yamada
We investigate key methodologies of Bhatnagar-Gross-Krook subgrid modeling for neutrino fast flavor conversions (FFC) in core-collapse supernova based on spherically symmetric Bolt…
Asymmetric emissions of neutrinos in the cooling of rotating proto-neutron stars
Laura Barrio, Kotaro Fujisawa, Ryuichiro Akaho +2
We evaluate global asymmetry in the luminosities of neutrinos emitted from rapidly-rotating proto-neutron stars (PNS's). We build axisymmetric models of PNS's in mechanical equilib…
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 +9
Neutrinos from supernovae, especially those emitted during the late phase of core collapse, are essential for understanding the final stages of massive star evolution. We have been…
Neutrino Constraints on Black Hole Formation in M31
Yudai Suwa, Ryuichiro Akaho, Yosuke Ashida +9
We investigate neutrino signals associated with black hole formation resulting from the gravitational collapse of massive stars, motivated by the candidate failed supernova M31-201…
Quasi-steady evolution of fast neutrino-flavor conversions
Jiabao Liu, Hiroki Nagakura, Masamichi Zaizen +3
In astrophysical environments such as core-collapse supernovae (CCSNe) and binary neutron star mergers (BNSMs), neutrinos potentially experience substantial flavor mixing due to th…
Impacts of Black-Hole-Forming Supernova Explosions on the Diffuse Neutrino Background
Ken'ichiro Nakazato, Ryuichiro Akaho, Yosuke Ashida +1
Flux spectrum, event rate, and experimental sensitivity are investigated for the diffuse supernova neutrino background (DSNB), which originates from past stellar collapses and is a…
Observing Supernova Neutrino Light Curves with Super-Kamiokande. V. Distance Estimation with Neutrinos
Yudai Suwa, Akira Harada, Masamitsu Mori +7
Neutrinos are pivotal signals in multi-messenger observations of supernovae (SNe). Recent advancements in the analysis method of supernova (SN) neutrinos, especially in quantitativ…
Universality of the Neutrino Collisional Flavor Instability in Core Collapse Supernovae
Jiabao Liu, Hiroki Nagakura, Ryuichiro Akaho +3
Neutrinos are known to undergo flavor conversion processes among the three flavors. The fast flavor conversion (FFC) has been the central piece of flavor conversions taking place i…
Collisional and Fast Neutrino Flavor Instabilities in Two-dimensional Core-collapse Supernova Simulation with Boltzmann Neutrino Transport
Ryuichiro Akaho, Jiabao Liu, Hiroki Nagakura +2
We present a comprehensive study on the occurrences of the collisional flavor instability (CFI) and the fast flavor instability (FFI) of neutrinos based on a two-dimensional (2D) c…
Detectability of Late-time Supernova Neutrinos with Fallback Accretion onto Protoneutron star
Ryuichiro Akaho, Hiroki Nagakura, Thierry Foglizzo
We investigate the late-time neutrino emission powered by fallback mass accretion onto proto-neutron star (PNS), using neutrino radiation-hydrodynamic simulations with full Boltzma…
Protoneutron Star Convection Simulated with a New General Relativistic Boltzmann Neutrino Radiation-Hydrodynamics Code
Ryuichiro Akaho, Akira Harada, Hiroki Nagakura +6
We investigate the protoneutron star (PNS) convection using our newly developed general relativistic Boltzmann neutrino radiation-hydrodynamics code. This is a pilot study for more…
Principal-Axis Analysis of the Eddington Tensor for the Early Post-Bounce Phase of Rotational Core-Collapse Supernovae
Wakana Iwakami, Akira Harada, Hiroki Nagakura +6
Using full Boltzmann neutrino transport, we performed two-dimensional (2D) core-collapse supernova simulations in axisymmetry for two progenitor models with 11.2M and 15.0M both ro…
Multidimensional Boltzmann Neutrino Transport Code in Full General Relativity for Core-collapse Simulations
Ryuichiro Akaho, Akira Harada, Hiroki Nagakura +6
We develop a neutrino transfer code for core-collapse simulations, that directly solves the multidimensional Boltzmann equations in full general relativity. We employ the discrete…