研究者詳細

顔写真

カシヤマ　カズミ
樫山　和己
Kazumi Kashiyama
所属
大学院理学研究科　天文学専攻　理論天体物理学講座
職名
准教授
学位

  • 博士（理学）（京都大学）

  • 修士（理学）（京都大学）

e-Rad 研究者番号
10785744

経歴 4

  • 2022年3月 ～ 継続中
    東北大学　大学院理学研究科 天文学専攻　准教授

  • 2016年9月 ～ 2022年3月
    東京大学　大学院数理科学研究科　助教

  • 2014年9月 ～ 2016年9月
    カリフォルニア州立大学バークレー校　NASA Einstein Fellow

  • 2012年4月 ～ 2014年9月
    ペンシルバニア州立大学　日本学術振興会海外特別研究員

学歴 2

  • 京都大学　大学院理学研究科　物理学・宇宙物理学専攻

    2007年4月 ～ 2012年3月

  • 京都大学　理学部

    2003年4月 ～ 2007年3月

研究キーワード 1

  • 宇宙物理学

研究分野 1

  • 自然科学一般 / 天文学 /

受賞 1

  1. 日本天文学会研究奨励賞

    2020年3月

論文 77

  1. Successive Partial Disruptions with Orbital Precession in a White Dwarf–Black Hole System for Repeating GRB 250702B

    Yuri Sato, Rin Oikawa, Kazuma Kato, Tatsuya Matsumoto, Kazumi Kashiyama

    The Astrophysical Journal Letters　2026年6月1日

    DOI： 10.3847/2041-8213/ae6a8f 　

  2. Blowouts of Nascent Wind Bubbles in Pulsar-driven Supernovae

    Mingxi Chen, Kazumi Kashiyama, Masato Sato

    The Astrophysical Journal　2026年4月10日

    DOI： 10.3847/1538-4357/ae4c58 　

  3. Spectral Uniformity of Little Red Dots: A Natural Outcome of Coevolving Seed Black Holes and Nascent Starbursts

    Kohei Inayoshi, Kohta Murase, Kazumi Kashiyama

    The Astrophysical Journal　2026年3月20日

    DOI： 10.3847/1538-4357/ae42ce 　

  4. A Necessary Condition for the Submergence of Proto–Neutron Star Magnetic Fields by Supernova Fallback

    Akihiro Inoue, Shinsuke Takasao, Kazumi Kashiyama, Yici Zhong, Hiroyuki R. Takahashi

    The Astrophysical Journal　2026年1月20日

    DOI： 10.3847/1538-4357/ae2c88 　

  5. Quasi-steady emission from repeating fast radio bursts can be explained by magnetar wind nebulae

    Mukul Bhattacharya, Kohta Murase, Kazumi Kashiyama

    Monthly Notices of the Royal Astronomical Society　2025年12月10日

    DOI： 10.1093/mnras/staf2175 　

  6. Gamma-Ray Burst Jets in Circumstellar Material: Dynamics, Breakout, and Diversity of Transients

    Hamid Hamidani, Kunihito Ioka, Kazumi Kashiyama, Masaomi Tanaka

    The Astrophysical Journal　2025年7月20日

    DOI： 10.3847/1538-4357/addd13 　

  7. EP240414a: A Gamma-Ray Burst Jet Weakened by an Extended Circumstellar Material

    Hamid Hamidani, Yuri Sato, Kazumi Kashiyama, Masaomi Tanaka, Kunihito Ioka, Shigeo S. Kimura

    The Astrophysical Journal Letters　2025年6月10日

    DOI： 10.3847/2041-8213/add99d 　

  8. Gravitational collapse of white dwarfs to neutron stars: From initial conditions to explosions with neutrino-radiation hydrodynamics simulations 査読有り

    Mori, Masamitsu, Sawada, Ryo, Suwa, Yudai, Tanikawa, Ataru, Kashiyama, Kazumi, Murase, Kohta

    Publications of the Astronomical Society of Japan　2025年2月

    DOI： 10.1093/pasj/psae104 　

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    Using general relativistic neutrino-radiation hydrodynamics simulations with the multi-group M1 scheme in one dimension, we investigate the collapse of massive, fully convective, and non-rotating white dwarfs (WDs), which are formed by accretion-induced collapse or merger-induced collapse, and the subsequent explosion. We produce initial WDs in hydrostatic equilibrium, which have super-Chandrasekhar mass and are about to collapse. The WDs have masses of <inline-formula><tex-math id="TM0001" notation="LaTeX">$1.6\, M_{\odot }$</tex-math></inline-formula> with different initial central densities specifically at <inline-formula><tex-math id="TM0002" notation="LaTeX">$1.0\times 10^{10}$</tex-math></inline-formula>, <inline-formula><tex-math id="TM0003" notation="LaTeX">$4.0\times 10^{9}$</tex-math></inline-formula>, <inline-formula><tex-math id="TM0004" notation="LaTeX">$2.0\times 10^{9}$</tex-math></inline-formula>, and <inline-formula><tex-math id="TM0005" notation="LaTeX">$1.0\times 10^{9}\:\mbox{g}\:\mbox{cm}^{-3}$</tex-math></inline-formula>. First, we examine the stability of initial WD in case weak interactions are turned off. Secondly, we calculate the collapse of WDs with weak interactions. We employ hydrodynamics simulations with Newtonian gravity in the first and second steps. Thirdly, we calculate the formation of neutron stars and accompanying explosions with general relativistic simulations. As a result, WDs with the highest density of <inline-formula><tex-math id="TM0006" notation="LaTeX">$10^{10}\:\mbox{g}\:\mbox{cm}^{-3}$</tex-math></inline-formula> collapse not by weak interactions but by the photodissociation of the iron, and three WDs with low central densities collapse by the electron capture as expected at the second step and succeed in the explosion with a small explosion energy of <inline-formula><tex-math id="TM0007" notation="LaTeX">$\sim\! 10^{48}\:$</tex-math></inline-formula>erg at the third step. By changing the surrounding environment of WDs, we find that there is a minimum value of ejecta masses, which is <inline-formula><tex-math id="TM0008" notation="LaTeX">$\sim\! 10^{-5}\, M_{\odot }$</tex-math></inline-formula>. With the most elaborate simulations of this kind so far, this value is one to two orders of magnitude smaller than previously reported values and is compatible with the estimated ejecta mass from FRB 121102....

  9. Exploring faint white dwarfs and the luminosity function with Subaru HSC and SDSS in Stripe 82

    Tian Qiu, Masahiro Takada, Naoki Yasuda, Akira Tokiwa, Kazumi Kashiyama, Yoshihisa Suzuki, Kenta Hotokezaka

    Monthly Notices of the Royal Astronomical Society　2024年11月26日

    DOI： 10.1093/mnras/stae2355 　

  10. On the X-ray efficiency of the white dwarf pulsar candidate ZTF J190132.9+145808.7

    Aya Bamba, Yukikatsu Terada, Kazumi Kashiyama, Shota Kisaka, Takahiro Minami, Tadayuki Takahashi

    Publications of the Astronomical Society of Japan　2024年8月1日

    DOI： 10.1093/pasj/psae041 　

  11. A Dynamical Model for IRAS 00500+6713: The Remnant of a Type Iax Supernova SN 1181 Hosting a Double Degenerate Merger Product WD J005311

    Takatoshi Ko, Hiromasa Suzuki, Kazumi Kashiyama, Hiroyuki Uchida, Takaaki Tanaka, Daichi Tsuna, Kotaro Fujisawa, Aya Bamba, Toshikazu Shigeyama

    The Astrophysical Journal　2024年7月1日

    DOI： 10.3847/1538-4357/ad4d99 　

  12. Exploring Low-mass Black Holes through Tidal Disruption Events in the Early Universe: Perspectives in the Era of the JWST, Roman Space Telescope, and LSST Surveys

    Kohei Inayoshi, Kazumi Kashiyama, Wenxiu Li, Yuichi Harikane, Kohei Ichikawa, Masafusa Onoue

    The Astrophysical Journal　2024年5月1日

    DOI： 10.3847/1538-4357/ad344c 　

  13. The Optically Thick Rotating Magnetic Wind from a Massive White Dwarf Merger Product. II. Axisymmetric Magnetohydrodynamic Simulations

    Yici Zhong, Kazumi Kashiyama, Shinsuke Takasao, Toshikazu Shigeyama, Kotaro Fujisawa

    The Astrophysical Journal　2024年3月1日

    DOI： 10.3847/1538-4357/ad1f5c 　

  14. Testing a stochastic acceleration model of pulsar wind nebulae: early evolution of a wind nebula associated with SN 1986J

    Shuta J Tanaka, Kazumi Kashiyama

    Monthly Notices of the Royal Astronomical Society　2023年8月21日

    DOI： 10.1093/mnras/stad2504 　

  15. MASTER OT J030227.28+191754.5: A Dwarf Nova at a Massive Oxygen–Neon White Dwarf System?

    Mariko Kimura, Kazumi Kashiyama, Toshikazu Shigeyama, Yusuke Tampo, Shinya Yamada, Teruaki Enoto

    The Astrophysical Journal　951　(2)　124-124　2023年7月1日

    出版者・発行元： American Astronomical Society

    DOI： 10.3847/1538-4357/acd933 　

    ISSN：0004-637X

    eISSN：1538-4357

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    Abstract We present timing and spectral analysis results of the NICER and NuSTAR observations of the dwarf nova MASTER OT J030227.28+191754.5 during the 2021–2022 outburst. The soft X-ray component was found to be dominated by blackbody radiation with a temperature of ∼30 eV and also showed prominent oxygen and neon emission lines. The blackbody luminosity exceeded 1034 erg s−1, which is consistent with theoretical predictions, and then decreased more than an order of magnitude in 3.5 days. The inferred abundances of oxygen and neon in the optically thin coronal region surrounding the central white dwarf (WD) are several times higher than the respective solar values. Although inconclusive, the abundance enrichment may originate from the WD, indicating that it may be mainly composed of oxygen and neon. Assuming that the blackbody radiation comes from the belt-shaped boundary layer between the WD and the accretion disk, we estimated the WD radius to be (2.9 ± 1.1) × 108 cm, which corresponds to the WD mass range of 1.15–1.34 M⊙. If the accretion continues for another ∼1 Gyr, the WD may experience an accretion-induced collapse into a neutron star and form a so-called black widow pulsar system.

  16. Gravitational Collapse of White Dwarfs to Neutron Stars. I. From Initial Conditions to Explosions with Neutrino-radiation Hydrodynamics Simulations

    Mori, Masamitsu, Sawada, Ryo, Suwa, Yudai, Tanikawa, Ataru, Kashiyama, Kazumi, Murase, Kohta

    2023年6月30日

    出版者・発行元： arXiv e-prints

    DOI： 10.48550/arXiv.2306.17381 　

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    This paper provides collapses of massive, fully convective, and non-rotating white dwarfs (WDs) formed by accretion-induced collapse or merger-induced collapse and the subsequent explosions with the general relativistic neutrino-radiation hydrodynamics simulations. We produce initial WDs in hydrostatic equilibrium, which have super-Chandrasekhar mass and are about to collapse. The WDs have masses of 1.6$M_\odot$ with different initial central densities specifically at $10^{10}$, $10^{9.6}$, $10^{9.3}$ and $10^{9.0}\,{\rm g\,cm^{-3 } }$. First, we check whether initial WDs are stable without weak interactions. Second, we calculate the collapse of WDs with weak interactions. We employ hydrodynamics simulations with Newtonian gravity in the first and second steps. Third, we calculate the formation of neutron stars and accompanying explosions with general relativistic simulations. As a result, WDs with the highest density of $10^{10}\,{\rm g\,cm^{-3 } }$ collapse not by weak interactions but by the photodissociation of the iron, and three WDs with low central densities collapse by the electron capture as expected at the second step and succeed in the explosion with a small explosion energy of $\sim 10^{48}$ erg at the third step. By changing the surrounding environment of WDs, we find that there is a minimum value of ejecta masses being $\sim 10^{-5}M_{\odot}$. With the most elaborate simulations of this kind so far, the value is one to two orders of magnitude smaller than previously reported values and is compatible with the estimated ejecta mass from FRB~121102....

  17. Modeling photometric variations due to a global inhomogeneity on an obliquely rotating star: Application to light curves of white dwarfs

    Yasushi Suto, Shin Sasaki, Masataka Aizawa, Kotaro Fujisawa, Kazumi Kashiyama

    Publications of the Astronomical Society of Japan　75　(1)　103-119　2022年12月9日

    出版者・発行元： Oxford University Press (OUP)

    DOI： 10.1093/pasj/psac093 　

    ISSN：0004-6264

    eISSN：2053-051X

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    Abstract We develop a general framework to compute photometric variations induced by the oblique rotation of a star with an axisymmetric inhomogeneous surface. We apply the framework to compute light curves of white dwarfs adopting two simple models of their surface inhomogeneity. Depending on the surface model and the location of the observer, the resulting light curve exhibits a departure from a purely sinusoidal curve that is observed for a fraction of white dwarfs. As a specific example, we fit our model to the observed phase-folded light curve of a fast-spinning white dwarf ZTF J190132.9+145808.7 (with a rotation period of 419 s). We find that the size and obliquity angle of the spot responsible for the photometric variation are Δθs ≈ 60° and θ⋆ ≈ 60° or 90°, respectively, implying an interesting constraint on the surface distribution of the magnetic field on white dwarfs.

  18. Fast optical flares from M dwarfs detected by a one-second-cadence survey with Tomo-e Gozen

    Masataka Aizawa, Kojiro Kawana, Kazumi Kashiyama, Ryou Ohsawa, Hajime Kawahara, Fumihiro Naokawa, Tomoyuki Tajiri, Noriaki Arima, Hanchun Jiang, Tilman Hartwig, Kotaro Fujisawa, Toshikazu Shigeyama, Ko Arimatsu, Mamoru Doi, Toshihiro Kasuga, Naoto Kobayashi, Sohei Kondo, Yuki Mori, Shin-ichiro Okumura, Satoshi Takita, Shigeyuki Sako

    Publications of the Astronomical Society of Japan　74　(5)　1069-1094　2022年10月3日

    出版者・発行元： Oxford University Press (OUP)

    DOI： 10.1093/pasj/psac056 　

    ISSN：0004-6264

    eISSN：2053-051X

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    Abstract We report on a one-second-cadence wide-field survey for M-dwarf flares using the Tomo-e Gozen camera mounted on the Kiso Schmidt telescope. We detect 22 flares from M3–M5 dwarfs with a rise time of 5 s ≲ trise ≲ 100 s and an amplitude of 0.5 ≲ ΔF/F⋆ ≲ 20. The flare light-curves mostly show steeper rises and shallower decays than those obtained from the Kepler one-minute cadence data and tend to have flat peak structures. Assuming a blackbody spectrum with a temperature of 9000–15000 K, the peak luminosities and energies are estimated to be 1029 erg s−1 ≲ Lpeak ≲ 1031 erg s−1 and 1031 erg ≲ Eflare ≲ 1034 erg, which constitutes the bright end of fast optical flares for M dwarfs. We confirm that more than $90\%$ of the host stars of the detected flares are magnetically active based on their Hα-emission-line intensities obtained by LAMOST. An estimated occurrence rate of detected flares is ∼0.7 per day per active star, indicating they are common in magnetically active M dwarfs. We argue that the flare light-curves can be explained by the chromospheric compression model: the rise time is broadly consistent with the Alfvén transit time of a magnetic loop with a length scale of lloop ∼ 104 km and a field strength of 1000 gauss, while the decay time is likely determined by the radiative cooling of the compressed chromosphere down near to the photosphere with a temperature of ≳ 10000 K. These flares from M dwarfs could be a major contamination source for a future search of fast optical transients of unknown types.

  19. X-Raying the Birth of Binary Neutron Stars and Neutron Star–Black Hole Binaries

    Kazumi Kashiyama, Ryo Sawada, Yudai Suwa

    The Astrophysical Journal　2022年8月1日

    DOI： 10.3847/1538-4357/ac7ff7 　

  20. On the Energy Source of Ultrastripped Supernovae

    Ryo Sawada, Kazumi Kashiyama, Yudai Suwa

    The Astrophysical Journal　2022年3月1日

    DOI： 10.3847/1538-4357/ac53ae 　

  21. Multi-wavelength constraints on the outflow properties of the extremely bright millisecond radio bursts from the galactic magnetar SGR 1935 + 2154

    Shotaro Yamasaki, Kazumi Kashiyama, Kohta Murase

    Monthly Notices of the Royal Astronomical Society　511　(3)　3138-3149　2022年2月2日

    出版者・発行元： Oxford University Press (OUP)

    DOI： 10.1093/mnras/stac234 　

    ISSN：0035-8711

    eISSN：1365-2966

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    ABSTRACT Extremely bright coherent radio bursts with millisecond duration, reminiscent of cosmological fast radio bursts, were codetected with anomalously-hard X-ray bursts from a Galactic magnetar SGR 1935 + 2154. We investigate the possibility that the event was triggered by the magnetic energy injection inside the magnetosphere, thereby producing magnetically-trapped fireball (FB) and relativistic outflows simultaneously. The thermal component of the X-ray burst is consistent with a trapped FB with an average temperature of ∼200–300 keV and size of ∼105 cm. Meanwhile, the non-thermal component of the X-ray burst and the coherent radio burst may arise from relativistic outflows. We calculate the dynamical evolution of the outflow, launched with an energy budget of 1039–1040 erg comparable to that for the trapped FB, for different initial baryon load η and magnetization σ0. If hard X-ray and radio bursts are both produced by the energy dissipation of the outflow, the outflow properties are constrained by combining the conditions for photon escape and the intrinsic timing offset ≲ 10 ms among radio and X-ray burst spikes. We show that the hard X-ray burst must be generated at rX ≳ 108 cm from the magnetar, irrespective of the emission mechanism. Moreover, we find that the outflow quickly accelerates up to a Lorentz factor of 102 ≲ Γ ≲ 103 by the time it reaches the edge of the magnetosphere and the dissipation occurs at 1012 cm ≲ rradio, X ≲ 1014 cm. Our results imply either extremely-clean (η ≳ 104) or highly-magnetized (σ0 ≳ 103) outflows, which might be consistent with the rarity of the phenomenon.

  22. AT 2018lqh: Black Hole Born from a Rotating Star?

    Daichi Tsuna, Kazumi Kashiyama, Toshikazu Shigeyama

    The Astrophysical Journal Letters　2021年12月1日

    DOI： 10.3847/2041-8213/ac3997 　

  23. Multiwavelength Emission from Magnetically Arrested Disks around Isolated Black Holes

    Shigeo S. Kimura, Kazumi Kashiyama, Kenta Hotokezaka

    The Astrophysical Journal Letters　2021年11月1日

    DOI： 10.3847/2041-8213/ac35dc 　

  24. ALMA and NOEMA constraints on synchrotron nebular emission from embryonic superluminous supernova remnants and radio–gamma-ray connection

    Kohta Murase, Conor M B Omand, Deanne L Coppejans, Hiroshi Nagai, Geoffrey C Bower, Ryan Chornock, Derek B Fox, Kazumi Kashiyama, Casey Law, Raffaella Margutti, Peter Mészáros

    Monthly Notices of the Royal Astronomical Society　508　(1)　44-51　2021年9月7日

    出版者・発行元： Oxford University Press (OUP)

    DOI： 10.1093/mnras/stab2506 　

    ISSN：0035-8711

    eISSN：1365-2966

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    ABSTRACT Fast-rotating pulsars and magnetars have been suggested as the central engines of superluminous supernovae (SLSNe) and fast radio bursts, and this scenario naturally predicts non-thermal synchrotron emission from their nascent pulsar wind nebulae (PWNe). We report results of high-frequency radio observations with ALMA and NOEMA for three SLSNe (SN 2015bn, SN 2016ard, and SN 2017egm), and present a detailed theoretical model to calculate non-thermal emission from PWNe with an age of ∼1−3 yr. We find that the ALMA data disfavours a PWN model motivated by the Crab nebula for SN 2015bn and SN 2017egm, and argue that this tension can be resolved if the nebular magnetization is very high or very low. Such models can be tested by future MeV–GeV gamma-ray telescopes such as AMEGO.

  25. Gravitational Wave Backgrounds from Coalescing Black Hole Binaries at Cosmic Dawn: An Upper Bound

    Kohei Inayoshi, Kazumi Kashiyama, Eli Visbal, Zoltán Haiman

    The Astrophysical Journal　2021年9月1日

    DOI： 10.3847/1538-4357/ac106d 　

  26. A Necessary Condition for Supernova Fallback Invading Newborn Neutron-star Magnetosphere

    Yici Zhong, Kazumi Kashiyama, Toshikazu Shigeyama, Shinsuke Takasao

    The Astrophysical Journal　2021年8月1日

    DOI： 10.3847/1538-4357/ac0a74 　

  27. Magnetically Arrested Disks in Quiescent Black Hole Binaries: Formation Scenario, Observable Signatures, and Potential PeVatrons

    Shigeo S. Kimura, Takahiro Sudoh, Kazumi Kashiyama, Norita Kawanaka

    The Astrophysical Journal　2021年7月1日

    DOI： 10.3847/1538-4357/abff58 　

  28. Multiwavelength View of the Type IIn Zoo: Optical to X-Ray Emission Model of Interaction-powered Supernovae

    Daichi Tsuna, Kazumi Kashiyama, Toshikazu Shigeyama

    The Astrophysical Journal　2021年6月1日

    DOI： 10.3847/1538-4357/abfaf8 　

  29. Late-time radio and millimeter observations of superluminous supernovae and long gamma-ray bursts: Implications for central engines, fast radio bursts, and obscured star formation

    T. Eftekhari, B. Margalit, C. M.B. Omand, E. Berger, P. K. Blanchard, P. Demorest, B. D. Metzger, K. Murase, M. Nicholl, V. A. Villar, P. K.G. Williams, K. D. Alexander, S. Chatterjee, D. L. Coppejans, J. M. Cordes, S. Gomez, G. Hosseinzadeh, B. Hsu, K. Kashiyama, R. Margutti, Y. Yin

    Astrophysical Journal　912　(1)　2021年5月1日

    出版者・発行元： IOP Publishing Ltd

    DOI： 10.3847/1538-4357/abe9b8 　

    ISSN：1538-4357 0004-637X

  30. Intermediate Luminosity Red Transients by Black Holes Born from Erupting Massive Stars

    Daichi Tsuna, Ayako Ishii, Naoto Kuriyama, Kazumi Kashiyama, Toshikazu Shigeyama

    The Astrophysical Journal　2020年7月15日

    DOI： 10.3847/2041-8213/aba0ac 　

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    We consider black hole formation in failed supernovae when a dense circumstellar medium (CSM) is present around the massive star progenitor. By utilizing radiation hydrodynamical simulations, we calculate the mass ejection of blue supergiants and Wolf-Rayet stars in the collapsing phase and the radiative shock occurring between the ejecta and the ambient CSM. We find that the resultant emission is redder and dimmer than normal supernovae (bolometric luminosity of 1040- ${10}^{41}\ \mathrm{erg}\ { { \rm{s } } }^{-1}$ , effective temperature of ∼5 × 103 K, and timescale of 10-100 days) and shows a characteristic power-law decay, which may comprise a fraction of intermediate luminosity red transients (ILRTs) including AT 2017be. In addition to searching for the progenitor star in the archival data, we encourage X-ray follow-up observations of such ILRTs ∼1-10 yr after the collapse, targeting the fallback accretion disk....

  31. Astrometric study of Gaia DR2 stars for interstellar communication

    Kazumi Kashiyama

    International Journal of Astrobiology　2020年4月17日

    DOI： 10.1017/s147355042000004x 　

    ISSN：1473-5504 1475-3006

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    <jats:title>Abstract</jats:title> <jats:p>We discuss the prospects of high precision pointing of our transmitter to habitable planets around Galactic main sequence stars. For an efficient signal delivery, the future sky positions of the host stars should be appropriately extrapolated with accuracy better than the beam opening angle Θ of the transmitter. Using the latest data release (DR2) of Gaia, we estimate the accuracy of the extrapolations individually for 4.7 × 10<jats:sup>7</jats:sup> FGK stars, and find that the total number of targets could be ~10<jats:sup>7</jats:sup> for the accuracy goal better than 1″. Considering the pairwise nature of communication, our study would be instructive also for SETI (Search for Extraterrestrial Intelligence), not only for sending signals outward.</jats:p>

  32. The Optically Thick Rotating Magnetic Wind from a Massive White Dwarf Merger Product

    Kazumi Kashiyama, Kotaro Fujisawa, Toshikazu Shigeyama

    The Astrophysical Journal　2019年12月10日

    DOI： 10.3847/1538-4357/ab4e97 　

    ISSN：1538-4357

  33. A Search for Late-time Radio Emission and Fast Radio Bursts from Superluminous Supernovae

    Law}, C.~J., Omand}, C.~M., Kashiyama}, K., Murase}, K., Bower, G.~C., Aggarwal}, K., Burke-Spolaor}, S., Butler}, B.~J., Demorest}, P., Lazio}, T., J, Linford}, J., Tendulkar}, S.~P., Rupen}, M.

    The Astrophysical Journal　886　(1)　24-24　2019年11月

    DOI： 10.3847/1538-4357/ab4adb 　

  34. Type IIn Supernova Light Curves Powered by Forward and Reverse Shocks

    Tsuna}, Daichi, Kashiyama}, Kazumi, Shigeyama, Toshikazu

    The Astrophysical Journal　884　(1)　87-87　2019年10月10日

    DOI： 10.3847/1538-4357/ab40ba 　

  35. Dust formation in embryonic pulsar-aided supernova remnants

    {Om, }, Conor M.~B., {Kashiyama}, Kazumi, {Murase}, Kohta

    Monthly Notices of the Royal Astronomical Society　484　(4)　2019年4月

    DOI： 10.1093/mnras/stz371 　

  36. Repulsion of fallback matter due to central energy source in supernova

    {Shigeyama}, Toshikazu, {Kashiyama}, Kazumi

    Publications of the Astronomical Society of Japan　70　(6)　107-107　2018年12月

    DOI： 10.1093/pasj/psy108 　

  37. Constraining very-high-energy and optical emission from FRB 121102 with the MAGIC telescopes

    MAGIC Collaboration, Acciari}, V.~A., Ansoldi}, S., Antonelli}, L.~A., Arbet Engels}, A., Arcaro}, C., Baack}, D., Babi{\'c, A, Banerjee}, B., Bangale}, P., Barres de Almeida}, U., Barrio}, J.~A., Becerra Gonz{\'a}lez}, J., Bednarek}, W., Bernardini}, E., Berti}, A., Besenrieder}, J., Bhattacharyya}, W., Bigongiari}, C., Biland}, A., Blanch}, O., Bonnoli}, G., Carosi}, R., Ceribella}, G., Chatterjee}, A., Colak}, S., Colin}, P., Colombo}, E., Contreras}, J., Cortina}, J., Covino}, S., Cumani}, P., D'Elia}, V., da Vela}, P., Dazzi}, F., de Angelis}, A., de Lotto}, B., Delfino}, M., Delgado}, J., di Pierro, F, Dom{\'\i}nguez}, A., Dominis Prester}, D., Dorner}, D., Doro}, M., Einecke}, S., Elsaesser}, D., Fallah Ramazani, V, Fattorini}, A., Fern{\'a}ndez-Barral}, A., Ferrara}, G., Fidalgo}, D., Foffano}, L., Fonseca}, M.~V., Font}, L., Fruck}, C., Gallozzi}, S., Garc{\'\i}a, o}pez, R.~J., Garczarczyk}, M., Gaug}, M., Giammaria}, P., Godinovi{\'c, N, Guberman}, D., Hadasch}, D., Hahn}, A., Hassan}, T., Herrera}, J., Hoang}, J., Hrupec}, D., Inoue}, S., Ishio}, K., Iwamura}, Y., Kubo}, H., Kushida}, J., Kuve{\v{z } }di{\'c, D, Lamastra}, A., Lelas}, D., Leone}, F., Lindfors}, E., Lombardi}, S., Longo}, F., L{\'o}pez, M, L{\'o}pez-Oramas}, A., Maggio}, C., Majumdar}, P., Makariev}, M., Maneva}, G., Manganaro}, M., Mannheim}, K., Maraschi}, L., Mariotti}, M., Mart{\'\i}nez, M, Masuda}, S., Mazin}, D., Minev}, M., Miranda}, J., M, Mirzoyan}, R., Molina}, E., Moralejo}, A., Moreno}, V., Moretti}, E., Neustroev}, V., Niedzwiecki}, A., Nievas Rosillo}, M., Nigro}, C., Nilsson}, K., Ninci}, D., Nishijima}, K., Noda}, K., Nogu{\'e}s}, L., Paiano}, S., Palacio}, J., Paneque}, D., Paoletti}, R., Paredes}, J.~M., Pedaletti}, G., Pe{\~n}il}, P., Peresano}, M., Persic}, M., Prada Moroni, P.~G., Prand, ini}, E., Puljak}, I., Garcia}, J.~R., Rhode}, W., Rib{\'o, Rico}, J., Righi}, C., Rugliancich}, A., Saha}, L., Saito}, T., Satalecka}, K., Schweizer}, T., Sitarek}, J., v{S } }nidari{\'c, I, Sobczynska}, D., Somero}, A., Stamerra}, A., Strzys}, M., Suri{\'c, T, Tavecchio}, F., Temnikov}, P., Terzi{\'c, T, Teshima}, M., Torres-Alb{\`a } }, N., Tsujimoto}, S., Vanzo}, G., Vazquez Acosta}, M., Vovk}, I., Ward}, J., Will}, M., Zari{\'c } }, D., Marcote}, B., Spitler, L.~G., Hessels}, J.~W.~T., Kashiyama}, K., Murase}, K., Bosch-Ramon}, V., Michilli}, D., Seymour}, A.

    Monthly Notices of the Royal Astronomical Society　481　(2)　2018年12月

    DOI： 10.1093/mnras/sty2422 　

  38. Scattered Short Gamma-Ray Bursts as Electromagnetic Counterparts to Gravitational Waves and Implications of GW170817 and GRB 170817A

    {Kisaka}, Shota, {Ioka}, Kunihito, {Kashiyama}, Kazumi, {Nakamura}, Takashi

    The Astrophysical Journal　867　(1)　39-39　2018年11月

    DOI： 10.3847/1538-4357/aae30a 　

    ISSN：0004-637X

    eISSN：1538-4357

  39. Radio transients from newborn black holes

    {Kashiyama}, Kazumi, {Hotokezaka}, Kenta, {Murase}, Kohta

    Monthly Notices of the Royal Astronomical Society　478　(2)　2018年8月

    DOI： 10.1093/mnras/sty1145 　

  40. Detectability of thermal neutrinos from binary neutron-star mergers and implications for neutrino physics

    {Kyutoku}, Koutarou, {Kashiyama}, Kazumi

    Physical Review D　97　(10)　103001-103001　2018年5月

    DOI： 10.1103/PhysRevD.97.103001 　

  41. Mass ejection in failed supernovae: variation with stellar progenitor

    Fern{\'a}ndez, Rodrigo, Quataert}, Elio, Kashiyama, Kazumi, Coughlin, Eric R.

    Monthly Notices of the Royal Astronomical Society　476　(2)　2018年5月

    DOI： 10.1093/mnras/sty306 　

  42. Double Neutron Star Mergers and Short Gamma-ray Bursts: Long-lasting High-energy Signatures and Remnant Dichotomy

    Murase}, Kohta, Toomey, Michael W., Fang}, Ke, Oikonomou, Foteini, Kimura, Shigeo S., Hotokezaka, Kenta, Kashiyama}, Kazumi, Ioka}, Kunihito, M{\'e}sz{\'a}ros, Peter

    The Astrophysical Journal　854　(1)　60-60　2018年2月

    DOI： 10.3847/1538-4357/aaa48a 　

  43. Radio emission from embryonic superluminous supernova remnants

    {Om, }, Conor M.~B., {Kashiyama}, Kazumi, {Murase}, Kohta

    Monthly Notices of the Royal Astronomical Society　474　(1)　2018年2月

    DOI： 10.1093/mnras/stx2743 　

  44. Detectability of Small-Scale Dark Matter Clumps with Pulsar Timing Arrays

    {Kashiyama}, Kazumi, {Oguri}, Masamune

    arXiv e-prints　2018年1月

    出版者・発行元： arXiv e-prints

    詳細を見る 詳細を閉じる

    We examine the capability of pulsar timing arrays (PTAs) to detect very small-scale clumps of dark matter (DM), which are a natural outcome of the standard cold dark matter (CDM) paradigm. A clump streaming near the Earth or a pulsar induces an impulsive acceleration to encode residuals on pulsar timing data. We show that, assuming the standard abundance of DM clumps predicted by the CDM model, small-scale DM clumps with masses from $\sim 10^{-11} M_\odot$ to $\sim 10^{-8} \ M_\odot$ can be detectable by a PTA observation for a few decades with ${\cal O}(100)$ of pulsars with a timing noise of ${\cal O}(10)$ ns located at $\gtrsim 3$ kpc away from the Galactic center, as long as these mass scales are larger than the cutoff scale of the halo mass function that is determined by the particle nature of DM. Our result suggests that PTAs can provide a unique opportunity for testing one of the most fundamental predictions of the CDM paradigm. In addition, the detections and non-detections can constrain the cutoff mass scale inherent to the DM model. <P />...

  45. Rapidly Rising Optical Transients from the Birth of Binary Neutron Stars

    {Hotokezaka}, Kenta, {Kashiyama}, Kazumi, {Murase}, Kohta

    The Astrophysical Journal　850　(1)　18-18　2017年11月

    DOI： 10.3847/1538-4357/aa8c7d 　

  46. GW 150914-like black holes as Galactic high-energy sources

    Ioka}, Kunihito, Matsumoto, Tatsuya, Teraki}, Yuto, Kashiyama}, Kazumi, Murase}, Kohta

    Monthly Notices of the Royal Astronomical Society　470　(3)　2017年9月

    DOI： 10.1093/mnras/stx1337 　

  47. Erratum: A burst in a wind bubble and the impact on baryonic ejecta: high-energy gamma-ray flashes and afterglows from fast radio bursts and pulsar-driven supernova remnants

    Murase}, Kohta, Kashiyama}, Kazumi, M{\'e}sz{\'a}ros, Peter

    Monthly Notices of the Royal Astronomical Society　467　(3)　2017年5月

    DOI： 10.1093/mnras/stx310 　

  48. Large-scale clustering as a probe of the origin and the host environment of fast radio bursts

    {Shirasaki}, Masato, {Kashiyama}, Kazumi, {Yoshida}, Naoki

    Physical Review D　95　(8)　083012-083012　2017年4月

    DOI： 10.1103/PhysRevD.95.083012 　

  49. Testing the Young Neutron Star Scenario with Persistent Radio Emission Associated with FRB 121102

    {Kashiyama}, Kazumi, {Murase}, Kohta

    The Astrophysical Journal Letters　839　(1)　2017年4月

    DOI： 10.3847/2041-8213/aa68e1 　

  50. Pulsar Wind Nebulae as a Source of Cosmic-Ray Electrons and Positrons

    {Kashiyama}, Kazumi

    Modelling Pulsar Wind Nebulae　446　279-279　2017年

    DOI： 10.1007/978-3-319-63031-1_12 　

  51. Gravitational wave background from Population III binary black holes consistent with cosmic reionization

    Inayoshi}, Kohei, Kashiyama}, Kazumi, Visbal, Eli a, Haiman, Zolt{\'a}n

    Monthly Notices of the Royal Astronomical Society　461　(3)　2016年9月

    DOI： 10.1093/mnras/stw1431 　

  52. A burst in a wind bubble and the impact on baryonic ejecta: high-energy gamma-ray flashes and afterglows from fast radio bursts and pulsar-driven supernova remnants

    Murase}, Kohta, Kashiyama}, Kazumi, M{\'e}sz{\'a}ros, Peter

    Monthly Notices of the Royal Astronomical Society　461　(2)　2016年9月

    DOI： 10.1093/mnras/stw1328 　

  53. Stellar Tidal Disruption Events by Direct-collapse Black Holes

    {Kashiyama}, Kazumi, {Inayoshi}, Kohei

    The Astrophysical Journal　826　(1)　80-80　2016年7月

    DOI： 10.3847/0004-637X/826/1/80 　

  54. Ultrafast Outflows from Black Hole Mergers with a Minidisk

    Murase}, Kohta, Kashiyama}, Kazumi, M{\'e}sz{\'a}ros, Peter and, Shoemaker}, Ian, Senno, Nicholas

    The Astrophysical Journal Letters　822　(1)　2016年5月

    DOI： 10.3847/2041-8205/822/1/L9 　

  55. Multi-messenger Tests for Fast-spinning Newborn Pulsars Embedded in Stripped-envelope Supernovae

    Kashiyama}, Kazumi, Murase}, Kohta, Bartos, Imre, Kiuchi}, Kenta, Margutti, Raffaella

    The Astrophysical Journal　818　(1)　94-94　2016年2月

    DOI： 10.3847/0004-637X/818/1/94 　

  56. Direct collapse black hole formation via high-velocity collisions of protogalaxies

    {Inayoshi}, Kohei, {Visbal}, Eli, {Kashiyama}, Kazumi

    Monthly Notices of the Royal Astronomical Society　453　(2)　2015年10月

    DOI： 10.1093/mnras/stv1654 　

  57. X-Raying Extended Emission and Rapid Decay of Short Gamma-Ray Bursts

    Kagawa}, Yasuaki, Yonetoku, Daisuke, Sawano, Tatsuya, Toyanago}, Asuka, Nakamura}, Takashi, Takahashi}, Keitaro, Kashiyama}, Kazumi, Ioka}, Kunihito

    The Astrophysical Journal　811　(1)　4-4　2015年9月

    DOI： 10.1088/0004-637X/811/1/4 　

  58. Fast luminous blue transients from newborn black holes

    Kashiyama}, Kazumi, Quataer, Elio

    Monthly Notices of the Royal Astronomical Society　451　(3)　2015年8月

    DOI： 10.1093/mnras/stv1164 　

  59. Optical Synchrotron Precursors of Radio Hypernovae

    Nakauchi}, Daisuke, Kashiyama}, Kazumi, Nagakura, Hiroki and, Suwa, Yudai, Nakamura}, Takashi

    The Astrophysical Journal　805　(2)　164-164　2015年6月

    DOI： 10.1088/0004-637X/805/2/164 　

  60. Gammy-Ray and Hard X-Ray Emission from Pulsar-aided Supernovae as a Probe of Particle Acceleration in Embryonic Pulsar Wind Nebulae

    Murase}, Kohta, Kashiyama}, Kazumi, Kiuchi, Kenta, Bartos, Imre

    The Astrophysical Journal　805　(1)　82-82　2015年5月

    DOI： 10.1088/0004-637X/805/1/82 　

  61. Soft X-Ray Extended Emissions of Short Gamma-Ray Bursts as Electromagnetic Counterparts of Compact Binary Mergers: Possible Origin and Detectability

    Nakamura}, Takashi, Kashiyama}, Kazumi, Nakauchi, Daisuke and, Suwa, Yudai, Sakamoto, Takanori, Kawai, Nobuyuki

    The Astrophysical Journal　796　(1)　13-13　2014年11月

    DOI： 10.1088/0004-637X/796/1/13 　

  62. Galaxy Mergers as a Source of Cosmic Rays, Neutrinos, and Gamma Rays

    Kashiyama}, Kazumi, M{\'e}sz{\'a}ros, Peter

    The Astrophysical Journal Letters　790　(1)　2014年7月

    DOI： 10.1088/2041-8205/790/1/L14 　

  63. Blue Supergiant Model for Ultra-long Gamma-Ray Burst with Superluminous-supernova-like Bump

    Nakauchi}, Daisuke, Kashiyama}, Kazumi, Suwa, Yudai a, Nakamura, Takashi

    The Astrophysical Journal　778　(1)　67-67　2013年11月

    DOI： 10.1088/0004-637X/778/1/67 　

  64. Cosmological Fast Radio Bursts from Binary White Dwarf Mergers

    Kashiyama}, Kazumi, Ioka}, Kunihito, M{\'e}sz{\'a}ros, Peter

    The Astrophysical Journal Letters　776　(2)　2013年10月

    DOI： 10.1088/2041-8205/776/2/L39 　

  65. Sub-PeV Neutrinos from TeV Unidentified Sources in the Galaxy

    {Fox}, D.~B., {Kashiyama}, K., {M{\'e}szar{\'o}s}, P.

    The Astrophysical Journal　774　(1)　74-74　2013年9月

    DOI： 10.1088/0004-637X/774/1/74 　

  66. Subphotospheric Neutrinos from Gamma-Ray Bursts: The Role of Neutrons

    Murase}, Kohta, Kashiyama}, Kazumi, M{\'e}sz{\'a}ros, Peter

    Physical Review Letters　111　(13)　131102-131102　2013年9月

    DOI： 10.1103/PhysRevLett.111.131102 　

  67. Neutron-Proton-Converter Acceleration Mechanism at Subphotospheres of Relativistic Outflows

    Kashiyama}, Kazumi, Murase}, Kohta, M{\'e}sz{\'a}ros, Peter

    Physical Review Letters　111　(13)　131103-131103　2013年9月

    DOI： 10.1103/PhysRevLett.111.131103 　

  68. On the Neutrino Non-detection of GRB 130427A

    Gao}, Shan, Kashiyama}, Kazumi, M{\'e}sz{\'a}ros, Peter

    The Astrophysical Journal Letters　772　(1)　2013年7月

    DOI： 10.1088/2041-8205/772/1/L4 　

  69. Luminous Supernova-like UV/Optical/Infrared Transients Associated with Ultra-long Gamma-Ray Bursts from Metal-poor Blue Supergiants

    Kashiyama}, Kazumi, Nakauchi, Daisuke, Suwa, Yudai an, Yajima, Hidenobu, Nakamura}, Takashi

    The Astrophysical Journal　770　(1)　8-8　2013年6月

    DOI： 10.1088/0004-637X/770/1/8 　

  70. High-energy Neutrino and Gamma-Ray Transients from Trans-relativistic Supernova Shock Breakouts

    Kashiyama}, Kazumi, Murase}, Kohta, Horiuchi, Shunsaku an, Gao}, Shan, M{\'e}sz{\'a}ros, Peter

    The Astrophysical Journal Letters　769　(1)　2013年5月

    DOI： 10.1088/2041-8205/769/1/L6 　

  71. Long-duration X-Ray Flash and X-Ray-rich Gamma-Ray Bursts from Low-mass Population III Stars

    Nakauchi}, Daisuke, Suwa, Yudai, Sakamoto, Takanori, Kashiyama}, Kazumi, Nakamura}, Takashi

    The Astrophysical Journal　759　(2)　128-128　2012年11月

    DOI： 10.1088/0004-637X/759/2/128 　

  72. Enhanced exploration for primordial black holes using pulsar timing arrays

    {Kashiyama}, Kazumi, {Seto}, Naoki

    Monthly Notices of the Royal Astronomical Society　426　(2)　2012年10月

    DOI： 10.1111/j.1365-2966.2012.21935.x 　

  73. Long duration X-ray flash from low mass population III stars 査読有り

    Daisuke Nakauchi, Yudai Suwa, Kazumi Kashiyama, Takashi Nakamura

    AIP Conference Proceedings　1480　397-399　2012年

    DOI： 10.1063/1.4754399 　

    ISSN：0094-243X 1551-7616

  74. Magnetar asteroseismology with long-term gravitational waves

    {Kashiyama}, Kazumi, {Ioka}, Kunihito

    Physical Review D　83　(8)　081302-081302　2011年4月

    DOI： 10.1103/PhysRevD.83.081302 　

  75. TeV Electron Spectrum for Probing Cosmic-ray Escape from a Supernova Remnant

    Kawanaka, Norita, Ioka}, Kunihito, Ohira, Yutaka, Kashiyama}, Kazumi

    The Astrophysical Journal　729　(2)　93-93　2011年3月

    DOI： 10.1088/0004-637X/729/2/93 　

  76. White dwarf pulsars as possible cosmic ray electron-positron factories

    Kashiyama}, Kazumi, Ioka}, Kunihito, Kawanaka, Norita

    Physical Review D　83　(2)　023002-023002　2011年1月

    DOI： 10.1103/PhysRevD.83.023002 　

  77. Quantum back reaction to asymptotically AdS black holes

    Kashiyama}, Kazumi, Tanahashi}, Norihiro, Flachi, Antonino, Tanaka, Takahiro

    Journal of High Energy Physics　2010　99-99　2010年1月

    DOI： 10.1007/JHEP01(2010)099 　

︎全件表示 ︎最初の5件までを表示

MISC 1

  1. 静穏時のブラックホール連星での強磁場降着流の形成と電磁波・宇宙線放射

    木村成生, 須藤貴弘, 樫山和己, 川中宣太

    日本天文学会年会講演予稿集　2021　2021年

    ISSN： 1347-0639

共同研究・競争的資金等の研究課題 7

  1. ニュートリノ天体からのマルチメッセンジャー信号に関する多角的理論研究

    木村 成生, 藤田 裕, 樫山 和己, 山崎 了, 堀内 俊作, 浅野 勝晃

    提供機関：Japan Society for the Promotion of Science

    制度名：Grants-in-Aid for Scientific Research

    研究種目：Grant-in-Aid for Transformative Research Areas (A)

    研究機関：Tohoku University

    2023年4月1日 ～ 2028年3月31日

  2. ONeMg白色矮星の重力崩壊と付随する突発・高エネルギー天体現象の研究

    樫山 和己, 諏訪 雄大, 守屋 尭

    提供機関：Japan Society for the Promotion of Science

    制度名：Grants-in-Aid for Scientific Research

    研究種目：Grant-in-Aid for Scientific Research (B)

    研究機関：Tohoku University

    2024年4月1日 ～ 2027年3月31日

  3. 高速電波バーストの標準モデルと宇宙論

    井岡 邦仁, 樫山 和己, 高橋 龍一, 柴田 大

    提供機関：Japan Society for the Promotion of Science

    制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

    研究種目：Grant-in-Aid for Scientific Research (A)

    研究機関：Kyoto University

    2022年4月1日 ～ 2026年3月31日

  4. 連星大質量星の進化の終末期と爆発現象

    諏訪 雄大, 樫山 和己, 井岡 邦仁

    2020年4月1日 ～ 2024年3月31日

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    近年、大質量星やコンパクト天体の連星系に関する観測的情報が飛躍的に増している。本研究では、近年の連星の知見を活かし、超新星爆発およびガンマ線バーストの爆発機構に迫ることを目標としている。当該年度は主に以下の成果を得た。 1. 近接連星による効果で外層を剥ぎ取られた大質量星の爆発計算を長時間行うことで、爆発物の一部が降り戻ってくるフォールバック効果の定量的評価を行った。このフォールバックを考慮に入れた元素合成計算や可視光の光度曲線計算を行った。 2. 上記で計算したフォールバックにより超新星爆発中心に存在する中性子星への加熱が起こることに着目し、X線帯域における光度をもとめた。また、連星へのフォールバック降着の時間発展について広い時間領域をカバーする物理モデルを構築した。

  5. 連星白色矮星合体残骸の進化計算と探査観測

    樫山 和己

    提供機関：Japan Society for the Promotion of Science

    制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

    研究種目：Grant-in-Aid for Scientific Research (C)

    2020年4月1日 ～ 2023年3月31日

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    木曽観測所Tomo-e Gozenカメラを用いた広視野高速読み出し測光観測を実施した。Tomo-e Gozenカメラの視野内に検出される天体について、ライトカーブの生成とノイズ抽出までを自動で行うパイプラインを作成し、それを用いて白色矮星と晩期型星の秒スケール変動探査を行った。 <BR> 白色矮星に関してはZwicky Transient Facility(ZTF)が2021年に報告したJ190132.9+145808.7からの単独白色矮星としては最短、およそ7分の周期変動を探査データから自動検出することに成功した。その他、観測視野内にとらえた白色矮星についてもライトカーブの解析を行い、それらをまとめた論文を準備している。また、京都大学岡山観測所のせいめい望遠鏡TriCCSカメラを用いた多バンド同時測光観測による連星白色矮星合体残骸候補の秒スケール変動探査を実施、現在データ解析を進めている。晩期型星に関しては秒スケールでライトカーブが立ち上がるフレア現象を新たに22例検出することに成功した。解析の結果、これらのフレアはこれまでに観測されたM型星の高速フレアの中では最も明るい種族であることがわかった。結果をまとめた論文を投稿準備中である。 <BR> 理論研究としては、連星白色矮星合体残骸からの磁気駆動風の２次元磁気流体シミュレーションに取り組んでいる。星表面から発射された物質が白色矮星磁気圏に一時的にトラップされ、その後、磁気リコネクションによって解放される、といった、1次元定常解（Kashiyama et al. 2019）の範囲では記述できない新たな効果を確認することができている。

  6. 大質量星連星における動的潮汐相互作用

    樫山 和己

    提供機関：Japan Society for the Promotion of Science

    制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

    研究種目：Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

    研究機関：The University of Tokyo

    2018年4月1日 ～ 2020年3月31日

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    2019年度は主に、1. 大質量星が重力崩壊を起こす直前の質量放出と重力崩壊時の爆発エジェクタの相互作用の理論計算を行い、特に重力崩壊に伴ってブラックホールが形成される場合に付随する突発天体現象とその検出可能性を議論した。また、2. 連星白色矮星合体の結果形成される強磁場高速回転合体残骸からの磁気遠心力駆動風の理論モデルを確立した。 <BR> 1.に関してはTsuna et al. 2019において重力崩壊直前の質量放出と重力崩壊じの爆発エジェクタが衝突した結果形成される衝撃波のダイナミクスを自己相似解を用いて記述、衝撃波圧縮を受けたガスからの輻射輸送を解いて、発生するUV/可視光/近赤外のライトカーブを計算する方法を確立した。特に、所謂forward shockとreverse shock両方の寄与を無矛盾に取り入れることに世界で初めて成功した。 <BR> 2.に関してはKashiyama et al. 2019において、2019年4月に発見が報告された白色矮星J005311 WDが放出する光速の10%もの速度をもつ星風に注目、強磁場高速回転白色矮星からの磁気遠心力駆動風の理論計算を行った。その結果、J005311は質量がおよそ1.2太陽質量、磁場強度がおよそ10^9 G、回転速度がおよそ10秒であることを明らかにした。このようなパラメータは連星白色矮星合体の結果形成される強磁場高速回転白色矮星の合体後数1000年の性質に符合し、J005311がこのような天体の第一例目であることを強く示唆している。

  7. パルサー駆動型爆発の多波長観測で探る中性子星形成の多様性

    樫山 和己

    提供機関：Japan Society for the Promotion of Science

    制度名：Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)

    研究種目：Grant-in-Aid for Young Scientists (B)

    研究機関：The University of Tokyo

    2017年4月1日 ～ 2020年3月31日

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    本研究では大質量星の重力崩壊に伴う中性子星の誕生、その100年以内の活動性を解き明かすための重要な道しるべをつけることができた。特に、1. 超高輝度超新星のパルサー駆動モデル検証へ向けた生後100年までのパルサー星雲放射の理論モデルの確立し、その過程で2. 高速電波バーストの起源天体としての超高輝度超新星残骸の提案、3. それらを検証するための電波観測を実施した。

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