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Affiliation |
Engineering educational research section Semiconductor Science and Applied Physics Program |
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Title |
Assistant Professor |
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Related SDGs |
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SUZUKI Hiromasa
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Papers 【 display / non-display 】
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Sakai Y., Yamada S., Mori K., Suzuki H., Sakemi H., Matsushima T., Kaneko S., Matsunaga K., Kobayashi S.B., Aoki H., Sato T.
Astrophysical Journal 1006 ( 1 ) 2026.7
Publishing type：Research paper (scientific journal) Publisher：Astrophysical Journal
We present a systematic imaging and spatially resolved spectral study of SN 1987A using Chandra observations obtained between 1999 and 2025. By combining multiepoch ACIS and HETG data, we investigate the long-term evolution of the remnant in both the soft and hard X-ray bands. To characterize the radial structure, we model the projected emission with a torus profile and derive its radius and width on the image plane. We find an energy dependence in the ring morphology: while the soft and hard bands exhibit similar structures at early epochs, the soft-band emission becomes systematically broader than the hard-band emission after the early 2010s. Furthermore, when considering the radius and width together, the soft-band emission shows an inward extension, suggesting an increasing contribution from interior and/or high-latitude emission components. The flux evolution of the Fe K line is consistent with previous XMM-Newton results, and we detect its presence already in earlier epochs (∼2007–2009) using combined Chandra spectra. Spatially resolved analysis further indicates that the Fe K emission is enhanced in the eastern region. These results provide a unified view of the long-term morphological and spectral evolution of SN 1987A and highlight the emergence of energy-dependent radial structure as a key feature in its late-time evolution.
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森 浩二, 鈴木 寛大
Astrophysical Journal 1006 ( 1 ) 93 2026.7
Language：English Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society
We present a systematic imaging and spatially resolved spectral study of SN 1987A using Chandra observations obtained between 1999 and 2025. By combining multiepoch ACIS and HETG data, we investigate the long-term evolution of the remnant in both the soft and hard X-ray bands. To characterize the radial structure, we model the projected emission with a torus profile and derive its radius and width on the image plane. We find an energy dependence in the ring morphology: while the soft and hard bands exhibit similar structures at early epochs, the soft-band emission becomes systematically broader than the hard-band emission after the early 2010s. Furthermore, when considering the radius and width together, the soft-band emission shows an inward extension, suggesting an increasing contribution from interior and/or high-latitude emission components. The flux evolution of the FeK line is consistent with previous XMM-Newton results, and we detect its presence already in earlier epochs (∼2007–2009) using combined Chandra spectra. Spatially resolved analysis further indicates that the FeK emission is enhanced in the eastern region. These results provide a unified view of the long-term morphological and spectral evolution of SN1987A and highlight the emergence of energy-dependent radial structure as a key feature in its late-time evolution.
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鈴木 寛大
Astrophysical Journal 1006 ( 1 ) 77 2026.7
Language：English Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society
Large High Altitude Air Shower Observatory (LHAASO) has reported 43 sub-PeV γ-ray sources, which are promising candidates for cosmic-ray (CR) accelerators above the PeV energy, commonly called PeVatrons. Multiwavelength observations are crucial for identifying the underlying particle species and estimating the CR energy content of these sources. In this work we investigate the region around LHAASO J1912+1014u (and HESS J1912+101) using Fermi-LAT γ-ray data and FUGIN CO data. We analyzed 15 yr of Fermi-LAT data in the 0.4–409.6 GeV energy range. By improving the standard Fermi-LAT diffuse emission model, we significantly reduced the large residuals around the source in the 1.6–12.8 GeV band. We detected a statistically significant excess above the diffuse background, which likely represents ≥10 GeV emission associated with the LHAASO/H.E.S.S. source. The GeV excess exhibits a hard spectrum (photon index of about 2.1) and is well reproduced by interstellar gas templates with systemic velocities of about 25 km s−1 or 60 km s−1. We performed a comprehensive fit to the GeV–TeV spectral energy distribution. Although a leptonic scenario can reproduce the observed spectrum, a hadronic scenario is favored once electron cooling is considered. The inferred CR proton spectrum has an index of ∼2.2, and the total CR proton energy above 1 GeV is (1–5) × 1049 erg, depending on the assumed velocity range of the associated interstellar gas. A stringent upper limit on diffuse X-ray emission further supports the proton PeVatron scenario.
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Audard M., Awaki H., Ballhausen R., Bamba A., Behar E., Boissay-Malaquin R., Brenneman L., Brown G.V., Corcoran M.F., Corrales L., Costantini E., Cumbee R., Diaz Trigo M., Done C., Dotani T., Ebisawa K., Eckart M.E., Eckert D., Eguchi S., Enoto T., Ezoe Y., Foster A., Fujimoto R., Fujita Y., Fukazawa Y., Fukushima K., Furuzawa A., Gallo L., García J.A., Goto E., Gu L., Guainazzi M., Hagino K., Hamaguchi K., Hatsukade I., Hayashi K., Hayashi T., Hell N., Hodges-Kluck E., Hornschemeier A., Ichinohe Y., Inoue S., Ishi D., Ishida M., Ishihara Y., Ishikawa K., Ishisaki Y., Junqueira F., Kaastra J., Kallman T., Kanemaru Y., Kara E., Katsuda S., Kelley R.L., Kilbourne C.A., Kitamoto S., Kobayashi S., Kohmura T., Kubota A., Leutenegger M., Loewenstein M., Maeda Y., Markevitch M., Matsumoto H., Matsushita K., McCammon D., McNamara B., Mernier F., Meulen B.V., Miller E.D., Miller J.M., Mitsuishi I., Miyamoto A., Mizumoto M., Mizuno T., Mori K., Mukai K., Murakami H., Mushotzky R., Nakajima H., Nakazawa K., Ness J.U., Nobukawa K., Nobukawa M., Noda H., Odaka H., Ogawa S., Ogorzałek A., Okajima T., Ota N., Paltani S., Petre R., Plucinsky P., Porter F.S., Pottschmidt K., Sato K., Sato T., Sawada M., Seta H., Shidatsu M.
Astrophysical Journal 1003 ( 2 ) 2026.6
Publishing type：Research paper (scientific journal) Publisher：Astrophysical Journal
The supermassive binary system, η Carinae, is experiencing enormous wind-driven mass loss at a rate unparalleled in the rest of the Galaxy. Their wind–wind collision (WWC) continuously produces shock heated, X-ray-emitting plasmas. The XRISM X-ray observatory observed the system in 2023 and 2024 when the X-ray emission began to increase toward periastron passage in 2025. This paper reports unprecedentedly high-resolution X-ray spectra in the Fe Kα band between 6.2 and 7.1 keV, obtained with the Resolve X-ray microcalorimeter. The hydrogen-like (Lyα) and helium-like (Heα) lines reveal three velocity components. Two of them are broadened with maximum velocities of 2000–3000 km s<sup>−1</sup>, likely originating from the postshock companion wind. The other is relatively narrow, with a Gaussian broadening of only ∼290 km s<sup>−1</sup> in 1σ, which may originate from the postshock companion wind at the WWC stagnation point or penetrating the primary wind. The Fe fluorescent lines exhibit a moderate blueshift and broadening with velocities at 100–200 km s<sup>−1</sup>, consistent with the primary wind’s velocity field. The spectra also confirm a Compton shoulder of the Heα line complex for the first time. Both fluorescing and scattering spectral profiles indicate that the binary system is seen from the companion side during these observations. The flux ratio of the Compton-scattering emission to the fluorescent line suggests substantial hydrogen depletion of the primary wind, expected from CNO-cycled hydrogen nuclear fusion gas.
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廿日出 勇, 森 浩二, 鈴木 寛大, 山内 誠
Astrophysical Journal 1003 156 2026.6
Language：English Publishing type：Research paper (scientific journal) Publisher：American Astronomical Society
The supermassive binary system, η Carinae, is experiencing enormous wind-driven mass loss at a rate unparalleled in the rest of the Galaxy. Their wind–wind collision (WWC) continuously produces shock heated, X-ray-emitting plasmas. The XRISM X-ray observatory observed the system in 2023 and 2024 when the X-ray emission began to increase toward periastron passage in 2025. This paper reports unprecedentedly high-resolution X-ray spectra in the Fe Kα band between 6.2 and 7.1 keV, obtained with the Resolve X-ray microcalorimeter. The hydrogen-like (Lyα) and helium-like (Heα) lines reveal three velocity components. Two of them are broadened with maximum velocities of 2000–3000 km s−1, likely originating from the postshock companion wind. The other is relatively narrow, with a Gaussian broadening of only ∼290 km s−1 in 1σ, which may originate from the postshock companion wind at the WWC stagnation point or penetrating the primary wind. The Fe fluorescent lines exhibit a moderate blueshift and broadening with velocities at 100–200 km s−1, consistent with the primary wind’s velocity field. The spectra also confirm a Compton shoulder of the Heα line complex for the first time. Both fluorescing and scattering spectral profiles indicate that the binary system is seen from the companion side during these observations. The flux ratio of the Compton-scattering emission to the fluorescent line suggests substantial hydrogen depletion of the primary wind, expected from CNO-cycled hydrogen nuclear fusion gas.
MISC 【 display / non-display 】
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XRISMニュース（5）： 国際相互較正 ―IACHEC年次集会2025開催記録― Reviewed
鈴木寛大
天文月報2025年11月号 2025.11
Authorship：Lead author Publishing type：Article, review, commentary, editorial, etc. (scientific journal)
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30分で分かる超新星残骸のX線精密分光 Invited Reviewed
鈴木寛大
天文教育 37 ( 4 ) 2025.7
Authorship：Lead author Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal)
Presentations 【 display / non-display 】
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XRISM/Xtend observations of diffuse X-ray emission around microquasars
Hiromasa Suzuki (U. Miyazaki), Naomi Tsuji (ICRR), Megumi Shidatsu (Ehime U.), Hideki Uchiyama (Shizuoka U.), Masayoshi Nobukawa (Nara U. of Edu.), Koji Mori (U. Miyazaki), Takaaki Tanaka (Konan U.), Shinya Yamada, Shogo Kobayashi (Rikkyo U.), Yoshihiro Ueda (Kyoto U.), Robert Petre (NASA/GSFC), Yusuke Sakai (Rikkyo U.), Toshihiro Takagi, Marina Yoshimoto (Ehime U.)
日本天文学会年会
Event date： 2026.3
Presentation type：Oral presentation (general)
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X線分光撮像衛星XRISM搭載軟X線撮像装置Xtendの現状(5)
野田博文, 小林翔悟A, 森浩二B, 中嶋大C, 冨田洋D, Takashi OkajimaE, 鈴木寛大B, 米山友景D, 内田裕之G, 萩野浩一H, 信川久実子I, 田中孝明J, 村上弘志K, 信川正順L, 内山秀樹M, 松本浩典N, 小高裕和N, 鶴剛G, 林多佳由G, 山内誠B, 廿日出勇B, 幸村孝由O, 山岡和貴P, 上田周太郎V, 石田学D, 前田良知D, 田村啓輔Q, R.Boissay-MalaquinQ, 佐藤寿紀R, 金丸善朗D, 伊師大貴D, 水野恒史S, 堂谷忠靖D, 尾崎正伸T, 常深博N, 東竜一J, 朝比奈遥C, 中村彰太郎C, 亀井貴光C, 福田将大C, 善本真梨那U, 袴田知宏N, 青柳美緒N, 島耕平N, 井上峻G, 青木悠馬I, 伊藤耶馬斗I, 樋口茉由O, 伊藤世織O, 中武隼汰O, 市川雄大B, 中野瑛子B, 岳本廉央B, 松島司B, 浦瀬怜香B, 倉嶋順B, 淵琴美B, 林田清N, 他 XRISM/Xtend チーム
日本物理学会春季大会
Event date： 2026.3
Presentation type：Oral presentation (general)
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超高層大気を観測するISS曝露部搭載X線SOI-CMOSカメラSUIMの地上試験
武田彩希, 鈴木寛大, 黒木瑛介, 田中富貴, 髙本巴瑠乃, 有川玲華, 柴田夢叶, 森浩二, 桒野慧, 信川久実子, 松井怜生, 竹島優人, 佐藤彰太郎, 青木悠馬, 鶴剛, 内田裕之, 勝田哲, 中澤知洋, 信川正順, 幸村孝由
日本物理学会春季大会
Event date： 2026.3
Presentation type：Oral presentation (general)
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超高層大気を観測するISS曝露部搭載X線SOI-CMOSカメラSUIMの開発状況
鈴木寛大, 武田彩希, 黒木瑛介, 田中富貴, 髙本巴瑠乃, 有川玲華, 柴田夢叶, 森浩二, 桒野慧, 信川久実子, 松井怜生, 竹島優人, 佐藤彰太郎, 青木悠馬, 鶴剛, 内田裕之, 勝田哲, 中澤知洋, 信川正順, 幸村孝由
日本物理学会春季大会
Event date： 2026.3
Presentation type：Oral presentation (general)
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A New Era in Plasma Diagnostics of Supernova Remnants with XRISM Invited International conference
Hiromasa Suzuki
XRISM International Conference 2025
Event date： 2025.10.20 - 2025.10.24
Presentation type：Oral presentation (invited, special)
Grant-in-Aid for Scientific Research 【 display / non-display 】
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観測装置の国際相互較正が可能にするX線精密分光時代の無衝突衝撃波の理解刷新
Grant number：24K17093 2024.04 - 2027.03
独立行政法人日本学術振興会 科学研究費基金 若手研究
Authorship：Principal investigator