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Engineering educational research section Applied Physics and Engineering Program |
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MORI Koji
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Degree 【 display / non-display 】
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Doctor (Science) ( 2002.6 Osaka University )
Research Areas 【 display / non-display 】
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Natural Science / Astronomy / X-ray and Gamma-ray astrophysics
Papers 【 display / non-display 】
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Hitomi HXT deconvolution imaging of the Crab Nebula dazzled by the Crab pulsar Reviewed
Morii M., Maeda Y., Awaki H., Hagino K., Ishida M., Mori K.
Publications of the Astronomical Society of Japan 76 ( 2 ) 272 - 284 2024.4
Language：English Publishing type：Research paper (scientific journal) Publisher：Publications of the Astronomical Society of Japan
We develop a new deconvolution method to recover the precise Crab Nebula image taken by the Hitomi HXT, suppressing the artifact due to the bright Crab pulsar. We extend the Richardson-Lucy method, introducing two components corresponding to the nebula and pulsar with regularization for smoothness and flux, respectively, and performing simultaneous deconvolution of multi-pulse-phase images. The structures, including the torus and jets, seen in the deconvolved nebula image at the lowest energy band of 3.6-15 keV appear consistent with those identified in the high-resolution Chandra X-ray image. Above 15 keV, we confirm NuSTAR's findings that the nebula size decreases in higher energy bands. We find that the north-east side of the nebula is fainter in higher energy bands. Our deconvolution method is applicable for any telescope images of faint diffuse objects containing a bright point source.
DOI： 10.1093/pasj/psae008
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Mapping thermal emission in the synchrotron-dominated supernova remnants G330.2+1.0, 3C58, and RX J1713.7-3946 Reviewed International coauthorship
Picquenot A., Williams B.J., Acero F., Mori K.
Astronomy and Astrophysics 683 2024.3
Language：English Publishing type：Research paper (scientific journal) Publisher：Astronomy and Astrophysics
Aims. Since the discovery of synchrotron X-ray emission from the shell of the supernova remnant (SNR) SN 1006, multiple observations from Chandra and XMM-Newton have shown that many young SNRs produce synchrotron emission in X-rays. Among those, a few peculiar SNRs have their X-ray emission largely dominated by synchrotron radiation, showing no or only faint traces of thermal emission. In this paper, we report our mapping of the thermal emission in three emblematic synchrotron-dominated SNRs: G330.2+1.0, 3C58, and RX J1713.7-3946. Methods. We used a blind source separation method able to retrieve faint components from X-ray data in the form of Chandra and XMM-Newton observations. The thermal candidates disentangled by the algorithm were then used to select regions of extraction. We then analyzed the extracted spectra to assess their physical nature. Results. We conclude that the components retrieved by the algorithm indeed represent the spatial distribution of the thermal emission in G330.2+1.0 and 3C58, and a likely thermal candidate in RX J1713.7-3946. Our findings confirm and expand on past studies.
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Yukumoto M., Mori K., Takeda A., Nishioka Y., Yonemura S., Izumi D., Iwakiri U., Tsuru T.G., Kurachi I., Hagino K., Arai Y., Kohmura T., Tanaka T., Kimura M., Fuchita Y., Yoshida T., Ikeda T.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 1060 2024.3
Language：English Publishing type：Research paper (scientific journal) Publisher：Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
We have been developing silicon-on-insulator (SOI) pixel detectors with a pinned depleted diode (PDD) structure, named “XRPIX”, for X-ray astronomy. The PDD structure is formed in a thick p-type substrate, to which high negative voltage is applied to make it fully depleted. A pinned p-well is introduced at the backside of the insulator layer to reduce a dark current generation at the Si-SiO2 interface and to fix the back-gate voltage of the SOI transistors. An n-well is further introduced between the p-well and the substrate to make a potential barrier between them and suppress a leakage current. An optimization study on the n-well dopant concentration is necessary because a higher dopant concentration could result in a higher potential barrier but also in a larger sense-node capacitance leading to a lower spectroscopic performance, and vice versa. Based on a device simulation, we fabricated five candidate chips having different n-well dopant concentrations. We successfully found out the best n-well design, which suppressed a large leakage current and showed satisfactory X-ray spectroscopic performance. Too low and too high n-well dopant concentration chips showed a large leakage current and degraded X-ray spectroscopic performance, respectively. We also found that the dependency of X-ray spectroscopic performance on the n-well dopant concentration can be largely explained by the difference in sense-node capacitance.
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Probing Shocked Ejecta in SN 1987A: A Novel Diagnostic Approach Using XRISM-Resolve Reviewed International coauthorship
Sapienza V., Miceli M., Bamba A., Orlando S., Lee S.H., Nagataki S., Ono M., Katsuda S., Mori K., Sawada M., Terada Y., Giuffrida R., Bocchino F.
Astrophysical Journal Letters 961 ( 1 ) 2024.1
Language：English Publishing type：Research paper (scientific journal) Publisher：Astrophysical Journal Letters
Supernova (SN) 1987A is one of the best candidates to exploit the capabilities of the freshly launched XRISM satellite. This celestial object offers the unique opportunity to study the evolution of an SN into a young supernova remnant. To date, the X-ray emission has been dominated by the shocked circumstellar medium, with no shocked ejecta firmly detected. However, recent studies provide compelling evidence that in the forthcoming years, the X-ray emission from SN 1987A will increasingly stem from the ejecta. Our aim is to assess the proficiency of the XRISM-Resolve high-resolution spectrometer in pinpointing signatures of the shocked ejecta in SN 1987A. Taking advantage of a self-consistent state-of-the-art magneto-hydrodynamic simulation that describes the evolution from SN 1987A to its remnant, we synthesized the XRISM-Resolve spectrum of SN 1987A, as it would be collected in the allocated observation during the performance verification phase, which is foreseen for 2024. Our predictions clearly show the leading role of shocked ejecta in shaping the profile of the emission lines. The Doppler broadening associated with the bulk motion along the line of sight of the rapidly expanding ejecta is shown to increase the line widths well above the values observed so far. The quantitative comparison between our synthetic spectra and the XRISM spectra will enable us to establish a strong connection between the broadened line emission and the freshly shocked ejecta. This, in turn, will allow us to retrieve the ejecta dynamics and chemical composition from the X-ray emission.
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Hagino K., Kitajima M., Kohmura T., Kurachi I., Tsuru T.G., Yukumoto M., Takeda A., Mori K., Nishioka Y., Tanaka T.
IEEE Transactions on Nuclear Science 70 ( 7 ) 1444 - 1450 2023.7
Language：English Publishing type：Research paper (scientific journal) Publisher：IEEE Transactions on Nuclear Science
The X-ray silicon-on-insulator (SOI) pixel sensor named X-ray pixel (XRPIX) has been developed for the future X-ray astronomical satellite focusing on relativistic universe and cosmic evolution (FORCE). XRPIX is capable of a wide-band X-ray imaging spectroscopy from below 1 keV to a few tens of keV with a good timing resolution of a few tens of s. However, it had a major issue with its radiation tolerance to the total ionizing dose (TID) effect because of its thick buried oxide layer due to the SOI structure. Although new device structures introducing pinned depleted diodes (PDDs) dramatically improved radiation tolerance, it remained unknown how radiation effects degrade the sensor performance. Thus, this article reports the results of a study of the degradation mechanism of XRPIX due to radiation using device simulations. In particular, mechanisms of increases in dark current and readout noise are investigated by simulation, taking into account the positive charge accumulation in the oxide layer and the increase in the surface recombination velocity at the interface between the sensor layer and the oxide layer. As a result, it is found that the depletion of the buried p-well (BPW) at the interface increases the dark current and that the increase in the sense-node capacitance increases the readout noise.
MISC 【 display / non-display 】
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SXS装置によるかに超新星残骸の熱的プラズマ放射探査 Invited
辻本匡弘、森浩二
天文月報 2019.6
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal) Publisher：日本天文学会
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超新星残骸から探るIa型超新星爆発の親星の金属量
森浩二
天文月報 2014.6
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (scientific journal) Publisher：日本天文学会
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宮崎県における高等学校と大学との物理教育に関する連絡会
森浩二、木村英二
大学の物理教育 2013.11
Language：Japanese Publishing type：Research paper, summary (national, other academic conference) Publisher：日本物理学会
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Ｘ線で見る星座
森浩二
数研出版株式会社サイエンスネット第37号 37 2009.11
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (other) Publisher：数研出版株式会社
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Ｘ線天文衛星 Suzaku および Chandra を用いた小マゼラン星雲中の超新星残骸 0103-72.6 の観測的研究
川井田英広, 木村結樹, 森浩二
宮崎大学工学部紀要 ( 37 ) 43 - 50 2008.8
Language：Japanese Publishing type：Article, review, commentary, editorial, etc. (bulletin of university, research institution) Publisher：宮崎大学工学部
Presentations 【 display / non-display 】
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The XRISM Xtend: Large FoV X-ray Imager Invited International coauthorship International conference
Koji Mori
21st Meeting of the High Energy Astrophysics Division
Event date： 2024.4.7 - 2024.4.12
Language：English Presentation type：Oral presentation (general)
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FORCE の概要と教訓 Invited
森浩二
第23回高宇連研究会
Event date： 2024.3.27 - 2024.3.29
Language：Japanese Presentation type：Oral presentation (general)
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超高層大気を観測するISS搭載X線SOI-CMOSピクセル検出器カメラの開発
武田彩希、森浩二、他
日本物理学会2024年春季大会
Event date： 2024.3.18 - 2024.3.21
Language：Japanese Presentation type：Oral presentation (general)
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CTA報告218：全体報告 International coauthorship
山本常夏、森浩二、他
日本物理学会2024年春季大会
Event date： 2024.3.18 - 2024.3.21
Language：Japanese Presentation type：Oral presentation (general)
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X線分光撮像衛星XRISM搭載X線望遠鏡(XMA)開発の現状 (9) International coauthorship
石田學、森浩二、他
日本物理学会2024年春季大会
Event date： 2024.3.18 - 2024.3.21
Language：Japanese Presentation type：Oral presentation (general)
Awards 【 display / non-display 】
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日本物理学会若手奨励賞
2009.3 日本物理学会
森浩二
Award type：Award from Japanese society, conference, symposium, etc. Country：Japan
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井上研究奨励賞
2005.2 井上科学振興財団
森浩二
Award type：Award from publisher, newspaper, foundation, etc. Country：Japan
Grant-in-Aid for Scientific Research 【 display / non-display 】
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終端衝撃波のＸ線撮像分光による銀河系内最強加速器「カニ星雲」の加速機構の解明
Grant number：21H01095 2021.04 - 2026.03
独立行政法人日本学術振興会 科学研究費補助金 基盤研究(B)
Authorship：Principal investigator
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カニ星雲のサブ秒角スケールでの精密X線分光による電磁流体加速機構の解明
Grant number：21J10842 2021.04 - 2023.03
独立行政法人日本学術振興会 科学研究費補助金 特別研究員奨励費
Authorship：Principal investigator
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超新星残骸のＸ線精密撮像分光から探るIa型超新星の親星の起源
2019.04 - 2020.03
科学研究費補助金 基盤研究(B)
Authorship：Principal investigator
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超新星残骸のＸ線精密撮像分光から探るIa型超新星の親星の起源
2018.04 - 2019.03
科学研究費補助金 基盤研究(B)
Authorship：Principal investigator
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宇宙最初期ブラックホールの探査研究を実現する衛星搭載Ｘ線精密イメージングの開拓
2017.04 - 2018.03
科学研究費補助金 新学術領域研究
Authorship：Coinvestigator(s)
SOI CMOS Ｘ線検出器の開発
Other research activities 【 display / non-display 】
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国立天文台ハワイ観測所 Subaru Seminars
2005.02
国立天文台ハワイ観測所において「Recent progress in X-ray studies of the Crab Pulsar Wind Nebula」というタイトルでセミナーをおこなった。
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大阪大学理学部X線天文グループセミナー
2004.12
大阪大学理学部X線天文グループに招かれて「パルサー星雲観測の最近の進展」というタイトルでセミナーをおこなった。
Available Technology 【 display / non-display 】
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Ｘ線天文衛星を用いた高エネルギー天体の観測的研究
Ｘ線に感度を持つ衛星搭載用半導体カメラの開発
地上で動作可能な放射線イメージングカメラの開発Home Page： 高エネルギー宇宙物理学研究室
Related fields where technical consultation is available：・ Ｘ線・ガンマ線・陽子・中性子を含む放射線イメージング
・ 人工衛星に搭載する機器開発一般Message：お手持ちの技術を宇宙開発・放射線測定等に応用したいという場合は、ぜひご連絡ください