43 results on '"Jun Hidaka"'
Search Results
2. Review of uncertainties in the cosmic supernova relic neutrino background
- Author
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T. Kajino, Luca Boccioli, Jun Hidaka, and Grant J. Mathews
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Physics ,Diffuse radiation ,Nuclear and High Energy Physics ,COSMIC cancer database ,Physics::Instrumentation and Detectors ,Black hole formation ,Astrophysics::High Energy Astrophysical Phenomena ,High Energy Physics::Phenomenology ,General Physics and Astronomy ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Neutron star ,Supernova ,Supergiant ,Neutrino ,Astrophysics::Galaxy Astrophysics - Abstract
We review the computation of and associated uncertainties in the current understanding of the relic neutrino background due to core-collapse supernovae, black hole formation and neutron star merger events. We consider the current status of uncertainties due to the nuclear equation of state (EoS), the progenitor masses, the source supernova neutrino spectrum, the cosmological star formation rate, the stellar initial mass function, neutrino oscillations, and neutrino self-interactions. We summarize the current viability of future neutrino detectors to distinguish the nuclear EoS and the temperature of supernova neutrinos via the detected relic supernova neutrino spectrum.
- Published
- 2020
3. Sterile neutrino dark matter and core-collapse supernovae
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Grant J. Mathews, Jun Hidaka, Toshitaka Kajino, and MacKenzie Warren
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Sterile neutrino ,Physics::Instrumentation and Detectors ,Astrophysics::High Energy Astrophysical Phenomena ,High Energy Physics::Phenomenology ,Dark matter ,FOS: Physical sciences ,Flux ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Electron ,Core (optical fiber) ,Supernova ,High Energy Physics::Experiment ,Neutrino ,Astrophysics - High Energy Astrophysical Phenomena ,Mixing (physics) - Abstract
We have explored the impact of sterile neutrino dark matter on core-collapse supernova explosions. We have included oscillations between electron neutrinos or mixed $\mu,\tau$ neutrinos and right-handed sterile neutrinos into a supernova model. We have chosen sterile neutrino masses and mixing angles that are consistent with sterile neutrino dark matter candidates as indicated by recent x-ray flux measurements. Using these simulations, we have explored the impact of sterile neutrinos on the core bounce and shock reheating. We find that, for ranges of sterile neutrino mass and mixing angle consistent with most dark matter constraints, the shock energy can be significantly enhanced and even a model that does not explode can be made to explode. In addition, we have found that the presence of a sterile neutrino may lead to detectable changes in the observed neutrino luminosities.
- Published
- 2017
4. Collective Neutrino Flavor Oscillations And Supernova Nucleosynthesis In Proton-rich Gas Flows
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Toshitaka Kajino, Hirokazu Sasaki, Baha Balantekin, Tomoyuki Maruyama, Jun Hidaka, Tomoya Takiwaki, and Y. Pehlivan
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Physics ,Nuclear physics ,Supernova ,Proton ,Nucleosynthesis ,Astrophysics::High Energy Astrophysical Phenomena ,High Energy Physics::Phenomenology ,High Energy Physics::Experiment ,Neutron ,Supernova nucleosynthesis ,Absorption (logic) ,Neutrino ,Neutrino oscillation - Abstract
In core-collapse supernovae, non-linear effects are caused by self-interacting neutrinos emitted from the proto-neutron star. These many-body effects induce collective neutrino oscillations and dramatic flavor changes in neutrino fluxes which will have crucial effects on $\nu$-process in outer layers or explosive nucleosynthesis such as $r$-process and $\nu p$-process in neutrino-driven winds. We have studied collective neutrino oscillations in the realistic 3 flavor multi-angle calculation using the simulation data of 1D explosion model. We have also applied these oscillation results to the nucleosynthesis in a proton-rich gas trajectory consistently. Especially, in normal neutrino mass hierarchy, we find the enhancement of the $\bar{\nu}_{e}$ flux caused by collective neutrino oscillations before $\nu p$-process proceeds actively. Therefore, $\nu p$-process is triggered by more free neutrons produced by the $\bar{\nu}_{e}$ absorption on protons and this nucleosynthesis is successful to raise up the abundances of lighter $p$-nucleus such as Se, Kr, and Sr greatly. Heavier $p$-nucleus like $^{92}\mathrm{Mo}$ and $^{96}\mathrm{Ru}$ are expected to enhanced by collective neutrino oscillations in more proton-rich and slower gas flows.
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- 2017
5. Stellar Abundances for Galactic Archaeology Database IV - Compilation of Stars in Dwarf Galaxies
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Kazuhiro Noda, Takuma Suda, Yutaka Katsuta, Yukari Ohtani, Kentaro Wada, Shimako Yamada, Masayuki Y. Fujimoto, Miyu Masuyama, Wako Aoki, and Jun Hidaka
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Metallicity ,Milky Way ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,computer.software_genre ,01 natural sciences ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,Dwarf galaxy ,Physics ,Database ,010308 nuclear & particles physics ,Star formation ,Local Group ,Astronomy and Astrophysics ,Archaeology ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Globular cluster ,Astrophysics::Earth and Planetary Astrophysics ,computer - Abstract
We have constructed the database of stars in the local group using the extended version of the SAGA (Stellar Abundances for Galactic Archaeology) database that contains stars in 24 dwarf spheroidal galaxies and ultra faint dwarfs. The new version of the database includes more than 4500 stars in the Milky Way, by removing the previous metallicity criterion of [Fe/H], Comment: 48 pages in single column format, 14 figures, accepted by PASJ. The SAGA database is available at http://sagadatabase.jp
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- 2017
6. Study of Red Supergiant and Supernova Rate Problems via Relic Supernova Neutrino Spectrum
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Grant J. Mathews, Jun Hidaka, and Toshitaka Kajino
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Physics ,Supernova ,Astronomy ,Red supergiant ,Astrophysics ,Neutrino ,Near-Earth supernova - Published
- 2017
7. Chemo-Dynamical Evolution of r-process Elements in the Local Group Galaxies
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Yuhri Ishimaru, Toshitaka Kajino, Jun Hidaka, Takayuki R. Saitoh, Michiko S. Fujii, and Yutaka Hirai
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Physics ,Galaxy group ,Galaxy formation and evolution ,Elliptical galaxy ,r-process ,Local Group ,Astrophysics ,Galaxy ,Luminosity function (astronomy) - Published
- 2017
8. Collective Neutrino-Flavor Oscillations and Application to Supernova Nucleosynthesis
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Baha Balantekin, Tomoyuki Maruyama, Toshitaka Kajino, Y. Pehlivan, Hirokazu Sasaki, Tomoya Takiwaki, and Jun Hidaka
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Physics ,Supernova nucleosynthesis ,Astrophysics ,Neutrino ,Flavor - Published
- 2017
9. EoS Dependence of the Relic Supernova Neutrino Spectrum
- Author
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Jun Hidaka, Grant J. Mathews, and Toshitaka Kajino
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Physics ,Equation of state ,Initial mass function ,010308 nuclear & particles physics ,Star formation ,Astrophysics::High Energy Astrophysical Phenomena ,Metallicity ,Nuclear Theory ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,01 natural sciences ,Supernova ,Neutrino detector ,Space and Planetary Science ,0103 physical sciences ,Neutrino ,Supergiant ,Nuclear Experiment ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
Understanding the mechanism of core-collapse supernova explosions requires knowledge of the nuclear equation of state (EoS). Recent multi-dimensional numerical simulations indicate that explosions are possible. Nevertheless, it is not yet fully understood which equation of state is realized in the proto-neutron star formed during SN explosions. We examine the EoS sensitivity of the relic supernova neutrino spectrum as a probe of the nuclear EoS. This sensitivity arises largely from the contribution to neutrino emission from failed supernovae. We consider a variety of astrophysical scenarios, which include different progenitor masses for a successful explosion, the cosmological star formation rate, starbursts, quiescent star formation, and the metallicity dependence of the initial mass function. We find that the EoS signature remains robust under a variety of conditions. We demonstrate the viability of future neutrino detectors to distinguish the nuclear EoS via the relic supernova neutrino spectrum.
- Published
- 2018
10. Early chemo-dynamical evolution of dwarf galaxies deduced from enrichment of r-process elements
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Yuhri Ishimaru, Michiko S. Fujii, Toshitaka Kajino, Takayuki R. Saitoh, Yutaka Hirai, and Jun Hidaka
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Physics ,010308 nuclear & particles physics ,Dwarf galaxy problem ,Local Group ,Astronomy ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Galaxy merger ,01 natural sciences ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,Dwarf spheroidal galaxy ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Galaxy group ,Astrophysics of Galaxies (astro-ph.GA) ,0103 physical sciences ,Elliptical galaxy ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Dwarf galaxy - Abstract
The abundance of elements synthesized by the rapid neutron-capture process (r-process elements) of extremely metal-poor (EMP) stars in the Local Group galaxies gives us clues to clarify the early evolutionary history of the Milky Way halo. The Local Group dwarf galaxies would have similarly evolved with building blocks of the Milky Way halo. However, how the chemo-dynamical evolution of the building blocks affects the abundance of r-process elements is not yet clear. In this paper, we perform a series of simulations using dwarf galaxy models with various dynamical times and total mass, which determine star-formation histories. We find that galaxies with dynamical times longer than 100 Myr have star formation rates less than $10^{-3} M_{\odot}$ yr$^{-1}$ and slowly enrich metals in their early phase. These galaxies can explain the observed large scatters of r-process abundance in EMP stars in the Milky Way halo regardless of their total mass. On the other hand, the first neutron star merger appears at a higher metallicity in galaxies with a dynamical time shorter than typical neutron star merger times. The scatters of r-process elements mainly come from inhomogeneity of the metals in the interstellar medium whereas the scatters of $\alpha$-elements are mostly due to the difference in the yield of each supernova. Our results demonstrate that the future observations of r-process elements in EMP stars will be able to constrain the early chemo-dynamical evolution of the Local Group galaxies., Comment: 14 pages, 17 figures, accepted for publication in MNRAS
- Published
- 2016
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11. Impact of sterile neutrino dark matter on core-collapse supernovae
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Grant J. Mathews, MacKenzie Warren, Jun Hidaka, Matthew Meixner, and Toshitaka Kajino
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Nuclear and High Energy Physics ,Sterile neutrino ,Physics::Instrumentation and Detectors ,Astrophysics::High Energy Astrophysical Phenomena ,Dark matter ,Flux ,FOS: Physical sciences ,Astrophysics ,Electron ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,High Energy Physics - Phenomenology (hep-ph) ,0103 physical sciences ,010303 astronomy & astrophysics ,Mixing (physics) ,Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,010308 nuclear & particles physics ,High Energy Physics::Phenomenology ,Astronomy and Astrophysics ,Observable ,Atomic and Molecular Physics, and Optics ,Supernova ,High Energy Physics - Phenomenology ,High Energy Physics::Experiment ,Neutrino ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We summarize the impact of sterile neutrino dark matter on core-collapse supernova explosions. We explore various oscillations between electron neutrinos or mixed $\mu-\tau$ neutrinos and right-handed sterile neutrinos that may occur within a core-collapse supernova. In particular, we consider sterile neutrino masses and mixing angles that are consistent with sterile neutrino dark matter candidates as indicated by recent X-ray flux measurements. We find that the interpretation of the observed 3.5 keV X-ray excess as due to a decaying 7 keV sterile neutrino that comprises 100\% of the dark matter would have almost no observable effect on supernova explosions. However, in the more realistic case in which the decaying sterile neutrino comprises only a small fraction of the total dark matter density due to the presence of other sterile neutrino flavors, WIMPs, etc., a larger mixing angle is allowed. In this case a 7 keV sterile neutrino could have a significant impact on core-collapse supernovae. We also consider mixing between $\mu-\tau$ neutrinos and sterile neutrinos. We find, however, that this mixing does not significantly alter the explosion and has no observable effect on the neutrino luminosities at early times., Comment: 18 pages, 6 figures, submitted to Modern Physics Letters A
- Published
- 2016
- Full Text
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12. Nuclear Equation of State and Asymmetric Neutrino Emission from Proto-Neutron Stars
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Tomoyuki Maruyama, Tomoya Takiwaki, Grant J. Mathews, Chung-Yeol Ryu, Jun Hidaka, Takami Kuroda, Toshitaka Kajino, Nobutoshi Yasutake, and Myung-Ki Cheoun
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Nuclear physics ,Physics ,Neutron star ,Solar neutrino ,Nuclear equation of state ,Solar neutrino problem ,Neutrino ,Neutrino oscillation - Published
- 2015
13. Equation of State of Proto-Neutron Star and Failed Supernova Neutrino
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Jutaro Suzuki, Grant J. Mathews, Jun Hidaka, and Toshitaka Kajino
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Physics ,Supernova ,Neutron star ,Equation of state ,Astronomy ,Astrophysics ,Neutrino ,Type II supernova - Published
- 2015
14. Enrichment of r-process elements in dwarf spheroidal galaxies in chemo-dynamical evolution model
- Author
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Yuhri Ishimaru, Toshitaka Kajino, Takayuki R. Saitoh, Michiko S. Fujii, Yutaka Hirai, and Jun Hidaka
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Physics ,Star formation ,Metallicity ,Milky Way ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics - Astrophysics of Galaxies ,Galaxy ,Abundance of the chemical elements ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Nucleosynthesis ,Astrophysics of Galaxies (astro-ph.GA) ,r-process ,Astrophysics::Solar and Stellar Astrophysics ,Stellar evolution ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
The rapid neutron-capture process (r-process) is a major process to synthesize elements heavier than iron, but the astrophysical site(s) of r-process is not identified yet. Neutron star mergers (NSMs) are suggested to be a major r-process site from nucleosynthesis studies. Previous chemical evolution studies however require unlikely short merger time of NSMs to reproduce the observed large star-to-star scatters in the abundance ratios of r-process elements relative to iron, [Eu/Fe], of extremely metal-poor stars in the Milky Way (MW) halo. This problem can be solved by considering chemical evolution in dwarf spheroidal galaxies (dSphs) which would be building blocks of the MW and have lower star formation efficiencies than the MW halo. We demonstrate that enrichment of r-process elements in dSphs by NSMs using an N-body/smoothed particle hydrodynamics code. Our high-resolution model reproduces the observed [Eu/Fe] by NSMs with a merger time of 100 Myr when the effect of metal mixing is taken into account. This is because metallicity is not correlated with time up to ~ 300 Myr from the start of the simulation due to low star formation efficiency in dSphs. We also confirm that this model is consistent with observed properties of dSphs such as radial profiles and metallicity distribution. The merger time and the Galactic rate of NSMs are suggested to be, Comment: 16 pages, 16 figures, accepted for publication in ApJ
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- 2015
- Full Text
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15. Asymmetric Neutrino Production in Strongly Magnetized Proto-Neutron Stars
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Myung-Ki Cheoun, Nobutoshi Yasutake, Jun Hidaka, Tomoya Takiwaki, Chung-Yeol Ryu, Takami Kuroda, Tomoyuki Maruyama, Grant J. Mathews, and Toshitaka Kajino
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Physics ,Nuclear and High Energy Physics ,Particle physics ,Nuclear Theory ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Flux ,FOS: Physical sciences ,Solar neutrino problem ,01 natural sciences ,7. Clean energy ,Magnetic field ,Nuclear physics ,Nuclear Theory (nucl-th) ,Neutron star ,0103 physical sciences ,Measurements of neutrino speed ,High Energy Physics::Experiment ,Neutrino ,Neutrino oscillation ,010303 astronomy & astrophysics ,Urca process - Abstract
We calculate the neutrino production cross-section through the direct URCA process in proto-neutron star matter in the presence of a strong magnetic field. We assume isoentropic conditions and introduce a new equation of state parameter-set in the relativistic mean-field approach that can reproduce neutron stars with $M > 1.96$ M$_\odot$ as required by observations. We find that the production process increases the flux of emitted neutrinos along the direction parallel to the magnetic field and decreases the flux in the opposite direction. This means that the neutrino flux asymmetry due to the neutrino absorption and scattering processes in a magnetic field becomes larger by the inclusion of the neutrino production process., 9 pages, 3 figures
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- 2014
16. Sterile neutrino oscillations in core-collapse supernovae
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Grant J. Mathews, Jun Hidaka, Toshitaka Kajino, MacKenzie Warren, and M. Meixner
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Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Nuclear and High Energy Physics ,Sterile neutrino ,Physics::Instrumentation and Detectors ,Solar neutrino ,Astrophysics::High Energy Astrophysical Phenomena ,Dark matter ,High Energy Physics::Phenomenology ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Solar neutrino problem ,Cosmic neutrino background ,Astrophysics - Solar and Stellar Astrophysics ,Measurements of neutrino speed ,High Energy Physics::Experiment ,Neutrino ,Neutrino oscillation ,Astrophysics - High Energy Astrophysical Phenomena ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
We have made core-collapse supernova simulations that allow oscillations between electron neutrinos (or their anti particles) with right-handed sterile neutrinos. We have considered a range of mixing angles and sterile neutrino masses including those consistent with sterile neutrinos as a dark matter candidate. We examine whether such oscillations can impact the core bounce and shock reheating in supernovae. We identify the optimum ranges of mixing angles and masses that can dramatically enhance the supernova explosion by efficiently transporting electron anti-neutrinos from the core to behind the shock where they provide additional heating leading to much larger explosion kinetic energies. We show that this effect can cause stars to explode that otherwise would have collapsed. We find that an interesting periodicity in the neutrino luminosity develops due to a cycle of depletion of the neutrino density by conversion to sterile neutrinos that shuts off the conversion, followed by a replenished neutrino density as neutrinos transport through the core.
- Published
- 2014
17. Asymmetric Neutrino Emission Process in Rapid Spin-Deceleration of Magnetized Proto-Neutron Stars
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Chung-Yeol Ryu, Jun Hidaka, Tomoyuki Maruyama, Toshitaka Kajino, Grant J. Mathews, Takami Kuroda, Nobutoshi Yasutake, and Myung-Ki Cheoun
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Physics ,Neutron star ,Observatory ,Astronomy ,Astrophysics ,Neutrino ,Education curriculum - Abstract
Tomoyuki Maruyama1, Jun Hidaka2, Toshitaka Kajino2, Nobutoshi Yasutake3, Takami Kuroda2, Myung-Ki Cheoun4, Chung-Yeol Ryu5 and Grant J. Mathews6 1College of Bioresource Sciences, Nihon University, Fujisawa 252-8510, Japan 2National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan 3Department of Physics, Chiba Institute of Technology, Narashino 275-0023, Japan 4Department of Physics, Soongsil University, Seoul, 156-743, Korea 5General Education Curriculum Center, Hanyang University, Seoul, 133-791, Korea 6Center of Astrophysics, University of Notre Dame, Notre Dame, IN 46556, USA
- Published
- 2014
18. Rapid spin deceleration of magnetized protoneutron stars via asymmetric neutrino emission
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Tomoya Takiwaki, Nobutoshi Yasutake, Grant J. Mathews, Myung-Ki Cheoun, C. Y. Ryu, Toshitaka Kajino, Jun Hidaka, Tomoyuki Maruyama, and Takami Kuroda
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Nuclear and High Energy Physics ,Particle physics ,Angular momentum ,Nuclear Theory ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Magnetic field ,Nuclear Theory (nucl-th) ,Nuclear physics ,High Energy Physics - Phenomenology ,Stars ,Neutron star ,High Energy Physics - Phenomenology (hep-ph) ,Astrophysics - Solar and Stellar Astrophysics ,Measurements of neutrino speed ,High Energy Physics::Experiment ,Neutrino ,Astrophysics - High Energy Astrophysical Phenomena ,Magnetic dipole ,Solar and Stellar Astrophysics (astro-ph.SR) ,Spin-½ - Abstract
We calculate the spin deceleration of proto-neutron stars by asymmetric neutrino absorption in the context of a fully relativistic mean field theory. We calculate for the first time the spin deceleration of neutron stars due to asymmetric neutrino absorption in a toroidal magnetic field configurations. We find a surprising effect that the deceleration can much larger for asymmetric neutrino absorption in a toroidal magnetic field than the usually presumed braking due to magnetic dipole radiation. This may explain the observation that magnetars appear to have had a more rapid deceleration in the past., Comment: 13 pages, 1 figure, 1 table
- Published
- 2014
19. Supernova Relic Neutrinos and the Supernova Rate Problem: Analysis of Uncertainties and Detectability of ONeMg and Failed Supernovae
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Jyutaro Suzuki, Toshitaka Kajino, Grant J. Mathews, and Jun Hidaka
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Physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Type II supernova ,Redshift ,Supernova ,Neutrino detector ,Space and Planetary Science ,Nucleosynthesis ,Astrophysics::Solar and Stellar Astrophysics ,High Energy Physics::Experiment ,Neutrino ,Neutrino oscillation ,Stellar evolution ,Astrophysics::Galaxy Astrophysics ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Direct measurements of the core-collapse supernova rate in the redshift range 0, Comment: 38 pages, 15 figures. Astrophysical Journal in Press
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- 2014
- Full Text
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20. Chemo-dynamical evolution of colliding dwarf spheroidal galaxies
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Jun Hidaka, Grant J. Mathews, S. Shibagaki, Yutaka Hirai, and Toshitaka Kajino
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Physics ,Chemical evolution ,Nucleosynthesis ,Star formation ,Metallicity ,Astronomy ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Gas cooling ,Collision ,Astrophysics::Galaxy Astrophysics ,Galaxy - Abstract
We present the first result from our project of chemo-dynamical simulations of dwarf spheroidal galaxies (dSphs). The chemical evolution of dSphs is affected by physical processes such as star formation and explosive nucleosynthesis as well as the dynamical merging histories among dSphs. It is thus important, first, to include nucleosynthetic information, and second, to carry out numerical simulations to clarify the chemo-dynamical evolution of dSphs. Therefore, we have implemented gas cooling, star formation rate, and chemical evolution to the N-body/smoothed particle hydrodynamic (SPH) code, Gadget-2 for the computation of chemo-dynamical evolution of dSphs. In particular, we study the collision effects of dSphs on the chemo-dynamical evolution. We derived star formation rate and metallicity distribution of an isolated model and a collided model. In the collided model, the two same mass dSphs are collided and merged. Both the isolated and collided models show the starburst at ∼ 0.3 Gyr after the start of the simulation. The star formation rate of the isolated model is continuous and quenched. In contrast, the starburst can be clearly seen at the time of the encounter of two dSphs in the collided model. The effects of collision can also be seen in the metallicity distribution. The peak of the metallicity distribution of the isolated model is at [Fe/H] ∼ −2.5, though the peak of the collided model is at [Fe/H] ∼ −1.6. The result implies that the collision of dSphs strongly affects the chemo-dynamical evolution of dSphs.
- Published
- 2014
21. Asymmetric neutrino production in magnetized proto-neutron stars in fully relativistic mean-field approach
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Myung-Ki Cheoun, Takami Kuroda, Jun Hidaka, Grant J. Mathews, Nobutoshi Yasutake, Chung-Yeol Ryu, Tomoya Takiwaki, Toshitaka Kajino, and Tomoyuki Maruyama
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Physics ,Solar mass ,Particle physics ,Astrophysics::High Energy Astrophysical Phenomena ,media_common.quotation_subject ,020206 networking & telecommunications ,02 engineering and technology ,Solar neutrino problem ,7. Clean energy ,Asymmetry ,Magnetic field ,Neutron star ,0202 electrical engineering, electronic engineering, information engineering ,Measurements of neutrino speed ,High Energy Physics::Experiment ,020201 artificial intelligence & image processing ,Neutrino ,Neutrino oscillation ,media_common - Abstract
We calculate the neutrino production cross-section in the proto-neutron-star matter under a strong magnetic field in the relativistic mean-field approach. We introduce a new parameter-set which can reproduce the 1.96 solar mass neutron star. We find that the production process increases emitted neutrinos along the direction parallel to the magnetic field and decrease those along its opposite direction. It means that resultant asymmetry due to the neutrino absorption and scattering process in the magnetic field becomes larger by the addition of the neutrino production process.
- Published
- 2014
22. IMPACT OF NEW GAMOW–TELLER STRENGTHS ON EXPLOSIVE TYPE IA SUPERNOVA NUCLEOSYNTHESIS
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Koichi Iwamoto, Ken'ichi Nomoto, Michael Famiano, Kanji Mori, Jun Hidaka, Toshio Suzuki, Takaharu Otsuka, Michio Honma, and Toshitaka Kajino
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Explosive material ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Electron ,01 natural sciences ,Nuclear physics ,Supernova ,Space and Planetary Science ,Nucleosynthesis ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Deflagration ,Supernova nucleosynthesis ,Astrophysics - High Energy Astrophysical Phenomena ,010306 general physics ,010303 astronomy & astrophysics ,Mass fraction ,Parametrization - Abstract
Recent experimental results have confirmed a possible reduction in the GT$_+$ strengths of pf-shell nuclei. These proton-rich nuclei are of relevance in the deflagration and explosive burning phases of Type Ia supernovae. While prior GT strengths result in nucleosynthesis predictions with a lower-than-expected electron fraction, a reduction in the GT$_+$ strength can result in an slightly increased electron fraction compared to previous shell model predictions, though the enhancement is not as large as previous enhancements in going from rates computed by Fuller, Fowler, and Newman based on an independent particle model. A shell model parametrization has been developed which more closely matches experimental GT strengths. The resultant electron-capture rates are used in nucleosynthesis calculations for carbon deflagration and explosion phases of Type Ia supernovae, and the final mass fractions are compared to those obtained using more commonly-used rates., Accepted for publication in Astrophysical Journal
- Published
- 2016
23. Chemo-dynamical evolution model: Enrichment of r-process elements in the Local Group dwarf galaxies
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Jun Hidaka, Takayuki R. Saitoh, Yuhri Ishimaru, Toshitaka Kajino, Yutaka Hirai, and Michiko S. Fujii
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Physics ,Star formation ,Computer Science::Information Retrieval ,Astronomy ,Local Group ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Dwarf spheroidal galaxy ,Smoothed-particle hydrodynamics ,Neutron star ,Space and Planetary Science ,Galaxy formation and evolution ,Astrophysics::Solar and Stellar Astrophysics ,r-process ,Astrophysics::Galaxy Astrophysics ,Dwarf galaxy - Abstract
Neutron star mergers are one of the candidate astrophysical site(s) of r-process. Several chemical evolution studies however pointed out that the observed abundance of r-process is difficult to reproduce by neutron star mergers. In this study, we aim to clarify the enrichment of r-process elements in the Local Group dwarf galaxies. We carry out numerical simulations of galactic chemo-dynamical evolution using an N-body/smoothed particle hydrodynamics code, ASURA. We construct a chemo-dynamical evolution model for dwarf galaxies assuming that neutron star mergers are the major source of r-process elements. Our models reproduce the observed dispersion in [Eu/Fe] as a function of [Fe/H] with neutron star mergers with a merger time of 100 Myr. We find that star formation efficiency and metal mixing processes during the first ≲ 300 Myr of galaxy evolution are important to reproduce the observations. This study supports that neutron star mergers are a major site of r-process.
- Published
- 2015
24. An anion channel from transverse tubular membranes incorporated into planar bilayers
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Toru Ide, Jun Hidaka, and Michiki Kasai
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Anion channel ,Stereochemistry ,Lipid Bilayers ,Biophysics ,Gating ,Biochemistry ,law.invention ,chemistry.chemical_compound ,Planar bilayer ,Chloride Channels ,law ,Animals ,Muscle, Skeletal ,Transverse tubule ,Membrane potential ,Chemistry ,Vesicle ,Conductance ,Cell Biology ,Membrane ,DIDS ,Chloride channel ,Rabbits ,Ion Channel Gating ,Torpedo - Abstract
Transverse tubular (TT) vesicles from rabbit skeletal muscle were incorporated into planar lipid bilayers to characterize the chloride channel. The single channel conductance of the channel was 40 pS in choline-Cl solution (cis, 300 mM/ 100 mM, trans). The gating rate of the channel does not depend on membrane voltage. The channel was blocked by stilbene derivatives (DIDS and SITS), which are known as inhibitors of voltage-dependent Cl− channels of the Torpedo electric organ, from both sides of the membrane. An inhibitor of voltage-dependent Cl− channels of skeletal muscles, 9-anthracene carboxylic acid (9-AC) inhibited the channel from the cis side of the membranes, which corresponded to the cytoplasmic space. Ethacrynic acid (EA), which is reported to inhibit Cl− conductance of the kidney and trachea, decreased the open probability of the TT Cl− channel concentration dependently. Indanyloxyacetic acid (IAA), which is also reported to be an inhibitor of kidney and trachea Cl− channels, decreased the single channel current without affecting open probability of the TT Cl− channel.
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- 1995
25. RED-SUPERGIANT AND SUPERNOVA RATE PROBLEMS: IMPLICATION FOR THE RELIC SUPERNOVA NEUTRINO SPECTRUM
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Grant J. Mathews, Jun Hidaka, and T. Kajino
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Diffuse radiation ,Physics ,010308 nuclear & particles physics ,Astronomy ,Astronomy and Astrophysics ,Astrophysics ,Type II supernova ,Near-Earth supernova ,01 natural sciences ,Cosmic neutrino background ,Supernova ,Space and Planetary Science ,0103 physical sciences ,Red supergiant ,Neutrino ,010303 astronomy & astrophysics - Published
- 2016
26. Astrophysical site(s) ofr-process elements in galactic chemodynamical evolution model
- Author
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Toshitaka Kajino, Michiko S. Fujii, Takayuki R. Saitoh, Yutaka Hirai, Yuhri Ishimaru, and Jun Hidaka
- Subjects
Physics ,Star formation ,QC1-999 ,Milky Way ,Metallicity ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Galaxy ,Galactic halo ,Galaxy formation and evolution ,Astrophysics::Solar and Stellar Astrophysics ,r-process ,Astrophysics::Galaxy Astrophysics ,Dwarf galaxy - Abstract
Astrophysical site(s) of rapid neutron-capture process ( r -process) is (are) not identified yet. Although core-collapse supernovae have been regarded as one of the possible candidates of the astrophysical site of r -process, nucleosynthesis studies suggest that serious difficulties in core-collapse supernovae to produce heavy elements with mass number of ≳110. Recent studies show that neutron star mergers (NSMs) can synthesize these elements due to their neutron rich environment. Some chemical evolution studies of the Milky Way halo, however, hardly reproduce the observed star-to-star scatters of the abundance ratios of r-process elements (e.g., Eu) in extremely metal-poor stars. This is because of their low rate (∼ 10 −4 yr −1 for a Milky Way size galaxy) and long merger time (≳ 100 Myr). This problem might be solved if the stars in the Galactic halo are consisted of the stars formed in dwarf galaxies where the star formation efficiencies were very low. In this study, we carry out numerical simulations of galactic chemo-dynamical evolution using an N-body/smoothed particle hydrodynamics code. We construct detailed chemo-dynamical evolution model for the Local Group dwarf spheroidal galaxies (dSphs) assuming that the NSMs are the major source of r -process elements. Our models successfully reproduce the observed dispersion in [Eu/Fe] as a function of [Fe/H] if we set merger time of NSMs, ≲ 300 Myr with the Galactic NSM rate of ∼ 10 −4 yr −1 . In addition, our results are consistent with the observed metallicity distribution of dSphs. In the early phase (≲1 Gyr) of galaxy evolution is constant due to low star formation efficiency of dSphs. This study supports the idea that NSMs are the major site of r -process nucleosynthesis.
- Published
- 2016
27. Asymmetric neutrino reaction and pulsar kick in magnetized proto-neutron stars in fully relativistic framework
- Author
-
Tomoyuki Maruyama, Toshitaka Kajino, Nobutoshi Yasutake, Jun Hidaka, Myung-Ki Cheoun, Chung-Yeol Ryu, and Grant J. Mathews
- Subjects
Physics ,Momentum ,Neutron star ,Supernova ,Pulsar ,Astrophysics::High Energy Astrophysical Phenomena ,media_common.quotation_subject ,Astrophysics ,Neutrino ,Nuclear matter ,Asymmetry ,media_common ,Magnetic field - Abstract
We calculate neutrino scattering and absorption on the hot and dense neutron-star matter with hyperons under the strong magnetic field using a perturbative approach. We find that the absorption cross-sections show a remarkable angular dependence. Its strength is reduced in the direction parallel to the magnetic field and enhanced in the opposite direction. This asymmetric variation becomes maximally 2.2% of entire neutrino momentum when the magnetic field is assumed as about 2 × 1017G. Since the pulsar kick after the supernova explosion may have relationships to this asymmetry, detailed discussions about the pulsar kick and the asymmetry are presented with the comparison to the observed kick velocities in a fully relativistic approach.
- Published
- 2012
28. Relativistic Mean-Field Treatment of Pulsar Kick from Neutrino Propagation in Magnetized Proto-Neutron
- Author
-
Tomoyuki Maruyama, Chung-Yeol Ryu, Grant J. Mathews, Jun Hidaka, Toshitaka Kajino, Nobutoshi Yasutake, and Myung-Ki Cheoun
- Subjects
Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Nuclear and High Energy Physics ,Particle physics ,Nuclear Theory ,media_common.quotation_subject ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Solar neutrino problem ,Asymmetry ,Magnetic field ,Nuclear physics ,Nuclear Theory (nucl-th) ,High Energy Physics - Phenomenology ,Neutron star ,High Energy Physics - Phenomenology (hep-ph) ,Astrophysics - Solar and Stellar Astrophysics ,Pulsar ,Measurements of neutrino speed ,High Energy Physics::Experiment ,Neutrino ,Astrophysics - High Energy Astrophysical Phenomena ,Neutrino oscillation ,Solar and Stellar Astrophysics (astro-ph.SR) ,media_common - Abstract
We make a perturbative calculation of neutrino scattering and absorption in hot and dense hyperonic neutron-star matter in the presence of a strong magnetic Field. We calculate that the absorption cross-sections in a fully relativistic mean-field theory. We find that there is a remarkable angular dependence, i.e. the neutrino absorption strength is reduced in a direction parallel to the magnetic Field and enhanced in the opposite direction. This asymmetry in the neutrino absorption is estimated to be as much as 2.2 % of the entire neutrino momentum for an interior magnetic Field of 2 x 10^{17} G. The pulsar kick velocities associated with this asymmetry are shown to be comparable to observed velocities., Comment: arXiv admin note: substantial text overlap with arXiv:1009.0976
- Published
- 2012
- Full Text
- View/download PDF
29. Characterization of a Cl−-Channel from Rabbit Transverse Tubules in the Planar Lipid Bilayer System
- Author
-
Michiki Kasai, Toru Ide, Jun Hidaka, Takahisa Taguchi, and Takashi Kawasaki
- Subjects
4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid ,Lipid Bilayers ,Biophysics ,Synthetic membrane ,Gating ,4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid ,In Vitro Techniques ,Biochemistry ,Membrane Potentials ,law.invention ,chemistry.chemical_compound ,Chlorides ,Chloride Channels ,law ,Animals ,Molecular Biology ,Membrane potential ,Chemistry ,Muscles ,Vesicle ,Cell Membrane ,Membrane Proteins ,Conductance ,Cell Biology ,Membrane ,DIDS ,Rabbits ,Ion Channel Gating ,Torpedo - Abstract
A Cl − -channel of the transverse tubule(TT) was incorporated into artificial planar lipid bilayers and its properties were investigated. The channel was found to have the following properties. (1) The single-channel conductance is 40 pS in choline-Cl solution. (2) The rate of gating of the channel does not depend on the membrane voltage. (3) The channel is blocked by stilbene derivatives (DIDS and SITS), which are known as inhibitors of voltage-dependent Cl − -channels of the Torpedo electric organ, from both sides of the membrane. (4) An inhibitor of voltage-dependent Cl − -channels of skeletal muscle, 9-anthracene carboxylic acid(9-AC), inhibits Cl − -current from the cis -side to which the TT vesicles were added.
- Published
- 1993
30. Astrophysical site(s) of r-process elements in galactic chemo-dynamical evolution model.
- Author
-
Yutaka Hirai, Yuhri Ishimaru, Saitoh, Takayuki R., Fujii, Michiko S., Jun Hidaka, and Toshitaka Kajino
- Subjects
NEUTRON capture ,SUPERNOVAE ,NUCLEOSYNTHESIS ,NEUTRON stars ,GALACTIC evolution ,ELLIPTICAL galaxies - Abstract
Astrophysical site(s) of rapid neutron-capture process (r-process) is (are) not identified yet. Although core-collapse supernovae have been regarded as one of the possible candidates of the astrophysical site of r-process, nucleosynthesis studies suggest that serious difficulties in core-collapse supernovae to produce heavy elements with mass number of ≳110. Recent studies show that neutron star mergers (NSMs) can synthesize these elements due to their neutron rich environment. Some chemical evolution studies of the Milky Way halo, however, hardly reproduce the observed star-to-star scatters of the abundance ratios of r-process elements (e.g., Eu) in extremely metal-poor stars. This is because of their low rate (~ 10
-4 yr-1 for a Milky Way size galaxy) and long merger time (≳ 100 Myr). This problem might be solved if the stars in the Galactic halo are consisted of the stars formed in dwarf galaxies where the star formation efficiencies were very low. In this study, we carry out numerical simulations of galactic chemo-dynamical evolution using an N-body/smoothed particle hydrodynamics code. We construct detailed chemo-dynamical evolution model for the Local Group dwarf spheroidal galaxies (dSphs) assuming that the NSMs are the major source of r-process elements. Our models successfully reproduce the observed dispersion in [Eu/Fe] as a function of [Fe/H] if we set merger time of NSMs, ≲ 300 Myr with the Galactic NSM rate of ~ 10-4 yr-1 . In addition, our results are consistent with the observed metallicity distribution of dSphs. In the early phase (≲1 Gyr) of galaxy evolution is constant due to low star formation efficiency of dSphs. This study supports the idea that NSMs are the major site of r-process nucleosynthesis. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
31. Sterile Neutrino-Enhanced Supernova Explosions
- Author
-
Jun Hidaka and George M. Fuller
- Subjects
Shock wave ,Nuclear and High Energy Physics ,Sterile neutrino ,Particle physics ,Physics::Instrumentation and Detectors ,Astrophysics::High Energy Astrophysical Phenomena ,Dark matter ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Atomic ,Particle and Plasma Physics ,High Energy Physics - Phenomenology (hep-ph) ,Invariant mass ,Nuclear ,Physics ,Quantum Physics ,Astrophysics (astro-ph) ,High Energy Physics::Phenomenology ,Molecular ,Type II supernova ,Atomic, Molecular, Nuclear, Particle And Plasma Physics ,Lepton number ,Nuclear & Particles Physics ,Supernova ,High Energy Physics - Phenomenology ,High Energy Physics::Experiment ,Neutrino ,Astronomical and Space Sciences - Abstract
We investigate the enhancement of lepton number, energy, and entropy transport resulting from active-sterile neutrino conversion $\nu_e\to\nu_s$ deep in the post-bounce supernova core followed by re-conversion $\nu_s\to\nu_e$ further out, near the neutrino sphere. We explicitly take account of shock wave and neutrino heating modification of the active neutrino forward scattering potential which governs sterile neutrino production. We find that the $\nu_e$ luminosity at the neutrino sphere could be increased by between $\sim 10 %$ and $\sim 100 %$ during the crucial shock re-heating epoch if the sterile neutrino has a rest mass and vacuum mixing parameters in ranges which include those required for viable sterile neutrino dark matter. We also find sterile neutrino transport-enhanced entropy deposition ahead of the shock. This `` pre-heating\rq\rq can help melt heavy nuclei and thereby reduce the nuclear photo-dissociation burden on the shock. Both neutrino luminosity enhancement and pre-heating could increase the likelihood of a successful core collapse supernova explosion., Comment: 12 pages, 4 figures
- Published
- 2007
32. Dark matter sterile neutrinos in stellar collapse: Alteration of energy/lepton number transport, and a mechanism for supernova explosion enhancement
- Author
-
Jun Hidaka and George M. Fuller
- Subjects
Nuclear and High Energy Physics ,Particle physics ,Sterile neutrino ,Astrophysics::High Energy Astrophysical Phenomena ,Star (game theory) ,FOS: Physical sciences ,Astrophysics ,Atomic ,Nuclear physics ,High Energy Physics - Phenomenology (hep-ph) ,Particle and Plasma Physics ,Affordable and Clean Energy ,Nuclear ,Neutrino oscillation ,Physics ,Quantum Physics ,Astrophysics (astro-ph) ,High Energy Physics::Phenomenology ,Center (category theory) ,Molecular ,Atomic, Molecular, Nuclear, Particle And Plasma Physics ,Nuclear & Particles Physics ,Lepton number ,High Energy Physics - Phenomenology ,High Energy Physics::Experiment ,Neutrino ,Astronomical and Space Sciences ,Energy (signal processing) ,Lepton - Abstract
We investigate matter-enhanced Mikheyev-Smirnov-Wolfenstein (MSW) active-sterile neutrino conversion in the $\nu_e \rightleftharpoons \nu_s$ channel in the collapse of the iron core of a pre-supernova star. For values of sterile neutrino rest mass $m_s$ and vacuum mixing angle $\theta$ (specifically, $0.5 {\rm keV}< m_s 5\times{10}^{-12}$) which include those required for viable sterile neutrino dark matter, our one-zone in-fall phase collapse calculations show a significant reduction in core lepton fraction. This would result in a smaller homologous core and therefore a smaller initial shock energy, disfavoring successful shock re-heating and the prospects for an explosion. However, these calculations also suggest that the MSW resonance energy can exhibit a minimum located between the center and surface of the core. In turn, this suggests a post-core-bounce mechanism to enhance neutrino transport and neutrino luminosities at the core surface and thereby augment shock re-heating: (1) scattering-induced or coherent MSW $\nu_e\to\nu_s$ conversion occurs deep in the core, at the first MSW resonance, where $\nu_e$ energies are large ($\sim 150$ MeV); (2) the high energy $\nu_s$ stream outward at near light speed; (3) they deposit their energy when they encounter the second MSW resonance $\nu_s\to\nu_e$ just below the proto-neutron star surface., Comment: 13 pages, 9 figures
- Published
- 2006
33. Stellar Abundances for Galactic Archaeology Database. IV. Compilation of stars in dwarf galaxies.
- Author
-
Takuma SUDA, Jun HIDAKA, Wako AOKI, Yutaka KATSUTA, Shimako YAMADA, FUJIMOTO, Masayuki Y., Yukari OHTANI, Miyu MASUYAMA, Kazuhiro NODA, and Kentaro WADA
- Subjects
- *
ASTRONOMY databases , *STELLAR evolution , *COSMIC abundances , *DWARF galaxies , *MILKY Way - Abstract
We have constructed a database of stars in Local Group galaxies using the extended version of the SAGA (Stellar Abundances for Galactic Archaeology) database that contains stars in 24 dwarf spheroidal galaxies and ultra-faint dwarfs. The new version of the database includes more than 4500 stars in the Milky Way, by removing the previous metallicity criterion of [Fe/H] ≤ -2.5, and more than 6000 stars in the Local Group galaxies. We examined the validity of using a combined data set for elemental abundances. We also checked the consistency between the derived distances to individual stars and those to galaxies as given in the literature. Using the updated database, the characteristics of stars in dwarf galaxies are discussed. Our statistical analyses of α-element abundances show that the change of the slope of the [α/Fe] relative to [Fe/H] (so-called "knee") occurs at [Fe/H]=-1.0±0.1 for the MilkyWay. The knee positions for selected galaxies are derived by applying the samemethod. The star formation history of individual galaxies is explored using the slope of the cumulative metallicity distribution function. Radial gradients along the four directions are inspected in six galaxies where we find no direction-dependence of metallicity gradients along the major and minor axes. The compilation of all the available data shows a lack of CEMP-s population in dwarf galaxies, while there may be some CEMP-no stars at [Fe/H]≲ -3 even in the very small sample. The inspection of the relationship between Eu and Ba abundances confirms an anomalously Ba-rich population in Fornax, which indicates a pre-enrichment of interstellar gas with r-process elements. We do not find any evidence of anti-correlations in O-Na and Mg-Al abundances, which characterizes the abundance trends in the Galactic globular clusters. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
34. Updates of the nuclear equation of state for core-collapse supernovae and neutron stars: effects of 3-body forces, QCD, and magnetic fields
- Author
-
Toshitaka Kajino, Nguyen Quynh Lan, Tomoyuki Maruyama, Grant J. Mathews, Matthew Meixner, Myung-Ki Cheoun, C. Y. Ryu, J. P. Olson, In-Saeng Suh, and Jun Hidaka
- Subjects
High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,History ,Equation of state ,Nuclear Theory ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Magnetar ,Computer Science Applications ,Education ,Magnetic field ,Nuclear Theory (nucl-th) ,Nuclear physics ,Neutron star ,Pulsar ,Nuclear force ,Neutrino ,Astrophysics - High Energy Astrophysical Phenomena ,Spin-½ - Abstract
We summarize several new developments in the nuclear equation of state for supernova simulations and neutron stars. We discuss an updated and improved Notre-Dame-Livermore Equation of State (NDL EoS) for use in supernovae simulations. This Eos contains many updates. Among them are the effects of 3- body nuclear forces at high densities and the possible transition to a QCD chiral and/or super-conducting color phase at densities. We also consider the neutron star equation of state and neutrino transport in the presence of strong magnetic fields. We study a new quantum hadrodynamic (QHD) equation of state for neutron stars (with and without hyperons) in the presence of strong magnetic fields. The parameters are constrained by deduced masses and radii. The calculated adiabatic index for these magnetized neutron stars exhibit rapid changes with density. This may provide a mechanism for star-quakes and flares in magnetars. We also investigate the strong magnetic field effects on the moments of inertia and spin down of neutron stars. The change of the moment of inertia associated with emitted magnetic flares is shown to match well with observed glitches in some magnetars. We also discuss a perturbative calculation of neutrino scattering and absorption in hot and dense hyperonic neutron-star matter in the presence of a strong magnetic field. The absorption cross-sections show a remarkable angular dependence in that the neutrino absorption strength is reduced in a direction parallel to the magnetic field and enhanced in the opposite direction. The pulsar kick velocities associated with this asymmetry comparable to observed pulsar velocities and may affect the early spin down rate of proto-neutron star magnetars with a toroidal field configuration., Comment: 6 pages, revised 1 figure, International Symposium "Exotic Nuclear Structure From Nucleons" (ENSFN 2012)
- Published
- 2013
35. Asymmetric Neutrino Production in Magnetized Proto-Neutron Stars in Fully Relativistic Mean-Field Approach.
- Author
-
Tomoyuki Maruyama, Toshitaka Kajino, Nobutoshi Yasutake, Jun Hidaka, Takami Kuroda, Tomoya Takiwaki, Myung-Ki Cheoun, Chung-Yeol Ryu, and Mathews, Grant J.
- Subjects
NEUTRINOS ,NEUTRON stars ,MEAN field theory ,RELATIVISTIC astrophysics ,NUCLEAR cross sections ,COSMIC magnetic fields ,ASYMMETRY (Chemistry) ,MAGNETARS - Abstract
We calculate the neutrino production cross-section in the proto-neutron-star matter under a strong magnetic field in the relativistic mean-field approach. We introduce a new parameter-set which can reproduce the 1.96 solar mass neutron star. We find that the production process increases emitted neutrinos along the direction parallel to the magnetic field and decrease those along its opposite direction. It means that resultant asymmetry due to the neutrino absorption and scattering process in the magnetic field becomes larger by the addition of the neutrino production process. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
36. Chemo-Dynamical Evolution of Colliding Dwarf Spheroidal Galaxies.
- Author
-
Yutaka Hirai, Toshitaka Kajino, Jun Hidaka, Shota Shibagaki, and Mathews, Grant J.
- Subjects
GALAXIES ,COSMOCHEMISTRY ,GALACTIC evolution ,GALACTIC dynamics ,STAR formation ,NUCLEOSYNTHESIS ,MATHEMATICAL models of hydrodynamics - Published
- 2014
- Full Text
- View/download PDF
37. A regularized N-body algorithm for gravitational collapse clustering
- Author
-
Jun Hidaka
- Subjects
Physics ,Classical mechanics ,Regularization (physics) ,Gravitational collapse ,Statistical physics ,Total energy ,Cluster analysis - Abstract
In N-body problem, it is necessary to regularize forces between close encountering particles to conserve their total energy. Without regularization, these particles has rapid change of their energy. We can, therefore, select close encountering particles looking at their energy and apply regularization to them. We discuss application of this scheme to spherically collapsing case.
- Published
- 2003
38. Identification of an anion channel protein from transverse tubules of rabbit skeletal muscle
- Author
-
Takahisa Taguchi, Michiki Kasai, Jun Hidaka, and Toru Ide
- Subjects
Chemistry ,General Neuroscience ,Blotting, Western ,Skeletal muscle ,Rabbit (nuclear engineering) ,Microtubules ,General Biochemistry, Genetics and Molecular Biology ,Ion ,Membrane Potentials ,Transverse plane ,medicine.anatomical_structure ,History and Philosophy of Science ,Chloride Channels ,Biophysics ,medicine ,Myocyte ,Animals ,Electrophoresis, Polyacrylamide Gel ,Rabbits ,ITGA7 ,Muscle, Skeletal - Published
- 1993
39. Rapid spin deceleration of magnetized protoneutron stars via asymmetric neutrino emission.
- Author
-
Tomoyuki Maruyama, Jun Hidaka, Toshitaka Kajino, Nobutoshi Yasutake, Takami Kuroda, Tomoya Takiwaki, Myung-Ki Cheoun, Chung-Yeol Ryu, and Mathews, Grant J.
- Subjects
- *
NEUTRON stars , *MEAN field theory , *SCATTERING (Physics) , *MAGNETIC fields , *MAGNETIC dipoles - Abstract
We estimate the maximum possible contribution to the early spin deceleration of protoneutron stars because of asymmetric neutrino absorption. We calculate the neutrino scattering in the context of a fully relativistic mean field theory and estimate for the first time the spin deceleration of neutron stars because of asymmetric neutrino absorption in a toroidal magnetic field configuration. We find that the deceleration can be much larger for asymmetric neutrino absorption in a toroidal magnetic field than the braking due to magnetic dipole radiation. Nevertheless, the effect is estimated to be less than the angular momentum loss due to the transport of magnetically locked material in the neutrino energized wind. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
40. IMPACT OF NEW GAMOW–TELLER STRENGTHS ON EXPLOSIVE TYPE IA SUPERNOVA NUCLEOSYNTHESIS.
- Author
-
Kanji Mori, Michael A. Famiano, Toshitaka Kajino, Toshio Suzuki, Jun Hidaka, Michio Honma, Koichi Iwamoto, Ken'ichi Nomoto, and Takaharu Otsuka
- Subjects
SUPERNOVAE ,NUCLEAR reactions ,NUCLEOSYNTHESIS ,COSMIC abundances ,BETA decay - Abstract
Recent experimental results have confirmed a possible reduction in the Gamow–Teller (GT
+ ) strengths of pf-shell nuclei. These proton-rich nuclei are of relevance in the deflagration and explosive burning phases of SNe Ia. While prior GT strengths result in nucleosynthesis predictions with a lower-than-expected electron fraction, a reduction in the GT+ strength can result in a slightly increased electron fraction compared to previous shell model predictions, though the enhancement is not as large as previous enhancements in going from rates computed by Fuller, Fowler, and Newman based on an independent particle model. A shell model parametrization has been developed that more closely matches experimental GT strengths. The resultant electron-capture rates are used in nucleosynthesis calculations for carbon deflagration and explosion phases of SNe Ia, and the final mass fractions are compared to those obtained using more commonly used rates. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
41. ENRICHMENT OF r-PROCESS ELEMENTS IN DWARF SPHEROIDAL GALAXIES IN CHEMO-DYNAMICAL EVOLUTION MODEL.
- Author
-
Yutaka Hirai, Yuhri Ishimaru, Takayuki R. Saitoh, Michiko S. Fujii, Jun Hidaka, and Toshitaka Kajino
- Subjects
ELLIPTICAL galaxies ,NEUTRON capture ,NEUTRON capture gamma ray spectroscopy ,GALAXIES ,TIDAL stripping (Astrophysics) - Abstract
The rapid neutron-capture process (r-process) is a major process for the synthesis of elements heavier than iron-peak elements, but the astrophysical site(s) of the r-process has not yet been identified. Neutron star mergers (NSMs) are suggested to be a major r-process site according to nucleosynthesis studies. Previous chemical evolution studies, however, required unlikely short merger times of NSMs to reproduce the observed large star-to-star scatters in the abundance ratios of r-process elements to iron: the [Eu/Fe] of extremely metal-poor stars in the Milky Way (MW) halo. This problem can be solved by considering chemical evolution in dwarf spheroidal galaxies (dSphs), which would be building blocks of the MW and have lower star formation efficiencies than the MW halo. We demonstrate the enrichment of r-process elements in dSphs by NSMs using an N-body/smoothed particle hydrodynamics code. Our high-resolution model reproduces the observed [Eu/Fe] due to NSMs with a merger time of 100 Myr when the effect of metal mixing is taken into account. This is because metallicity is not correlated with time ∼300 Myr from the start of the simulation due to the low star formation efficiency in dSphs. We also confirm that this model is consistent with observed properties of dSphs such as radial profiles and metallicity distribution. The merger time and the Galactic rate of NSMs are suggested to be ≲300 Myr and ∼10
−4 year−1 , respectively, which are consistent with the values suggested by population synthesis and nucleosynthesis studies. This study supports the argument that NSMs are the major astrophysical site of the r-process. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
42. Asymmetric neutrino production in strongly magnetized proto-neutron stars.
- Author
-
Tomoyuki Maruyama, Myung-Ki Cheoun, Jun Hidaka, Toshitaka Kajino, Kuroda, Takami, Mathews, Grant J., Chung-Yeol Ryu, Tomoya Takiwaki, and Nobutoshi Yasutake
- Subjects
- *
NEUTRON stars , *STELLAR magnetic fields , *NEUTRINOS , *NUCLEAR cross sections , *EQUATIONS of state , *RELATIVISTIC astrophysics - Abstract
We calculate the neutrino production cross-section through the direct URCA process in proto-neutron star matter in the presence of a strong magnetic field. We assume isoentropic conditions and introduce a new equation of state parameter set in the relativistic mean-field approach that can allow a neutron star mass up to 2.1M⊙ as required from observations. We find that the production process increases the flux of emitted neutrinos along the direction parallel to the magnetic field and decreases the flux in the opposite direction. This means that the neutrino flux asymmetry due to the neutrino absorption and scattering processes in a magnetic field becomes larger by the inclusion of the neutrino production process. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
43. Sterile neutrino oscillations in core-collapse supernovae.
- Author
-
Warren, MacKenzie L., Meixner, Matthew, Mathews, Grant, Jun Hidaka, and Toshitaka Kajino
- Subjects
- *
STERILE neutrinos , *SUPERNOVAE , *OSCILLATIONS , *ELECTRONIC antineutrino , *ELECTRON transport - Abstract
We have made core-collapse supernova simulations that allow oscillations between electron neutrinos (or their antiparticles) with right-handed sterile neutrinos. We have considered a range of mixing angles and sterile neutrino masses including those consistent with sterile neutrinos as a dark matter candidate. We examine whether such oscillations can impact the core bounce and shock reheating in supernovae. We identify the optimum ranges of mixing angles and masses that can dramatically enhance the supernova explosion by efficiently transporting electron antineutrinos from the core to behind the shock, where they provide additional heating leading to much larger explosion kinetic energies. We show that this effect can cause stars to explode that otherwise would have collapsed. We find that an interesting periodicity in the neutrino luminosity develops due to a cycle of depletion of the neutrino density by conversion to sterile neutrinos that shuts off the conversion, followed by a replenished neutrino density as neutrinos transport through the core. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
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