研究者業績
基本情報
論文
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宇宙航空研究開発機構研究開発報告: 宇宙科学情報解析論文誌 JAXA-RR-22-009(12) 31-40 2023年2月28日 査読有り超伝導の原理に基づく論理回路の一種である，単一磁束量子回路の動作を説明するためのインタラクティブ可視化手法について述べる．宇宙探査に関わる将来構想のひとつとして，単一磁束量子回路を用いたデバイスを宇宙機に搭載することが検討されている．単一磁束量子回路はデバイスの動作に係る電力消費が極めて小さく，また演算速度の高速化も期待されている．一方で単一磁束量子回路はCPU やメモリ等，半導体デバイスの論理回路と動作原理が大きく異なるため，その理解の助けとなるような可視化ツールが有用であると期待される．本稿においては，単一磁束量子回路の動作について，WebGL ベースのAPI 等のJavaScript を用いたインタラクティブ可視化アプリケーションを構築し，その課題や将来展望等について検討した．
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宇宙航空研究開発機構研究開発報告: 宇宙科学情報解析論文誌 JAXA-RR-14-009(4) 105-125 2015年3月31日 査読有りDARTS (http://darts.jaxa.jp/)は, JAXAの様々な科学衛星のデータを研究用に公開するデータアーカイブシステムであり, 宇宙科学研究所科学衛星運用・データ利用センター(C-SODA)が運用している. 我々は, 赤外線天文衛星「あかり」の全天サーベイ観測によって得られた2次元画像(全天マップ)を公開するための検索機能付きウェブインターフェースを開発している. 全天マップは, 多数の画像ファイルがタイル状に並んで全天球面をカバーするように構成されており, それぞれの画像は数度平方程度の天域を占めている. 本検索機能において, ユーザーに指定された領域を一部でも含む画像ファイルは全て検索結果として返されるものとする. そのような検索を実現するため, 各画像内を多数の小さな矩形領域に分割して各領域の中心点を直交座標系で表し, その座標値をデータベースに登録するという方法が採用される. この方法は, HEALPixのような外部の天球分割ライブラリが不要で, 天の両極が特異点にならず, かつ任意の座標系を用いた高速検索が可能という利点を持つ.開発と維持管理のコストを低減させるため, われわれはあかりカタログ検索の仕組みを本検索機能に応用し, またPHPとPostgreSQLを用いることによって本機能を実装する.
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宇宙航空研究開発機構研究開発報告: 宇宙科学情報解析論文誌 JAXA-RR-13-010(3) 17-26 2014年3月31日 査読有り責任著者GSTOS (Generic Spacecraft Test and Operations Software; 汎用衛星試験運用ソフトウェア) は，ISAS (Institute of Space and Aeronautical Science) の今後の衛星の試験と運用に使用される汎用のソフトウェアであり，SIB2 (Spacecraft Information Base version 2) に基づき動作する．SIB2/GSTOS-1 プロジェクトは，SPRINT-A, ASTRO-H, Bepi/MMO 向けのSIB2/GSTOSを開発するプロジェクトである．本論文では，SIB2/GSTOS-1 プロジェクトが目指すゴール，従来のISAS における典型的な衛星試験・運用システムに対する改善点を述べるとともに，現在までの開発状況，今後の課題について述べる．
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SOLAR PHYSICS AND SPACE WEATHER INSTRUMENTATION V 8862 2013年 査読有りWe present a design progress of the Solar UV-Vis-IR Telescope (SUVIT) aboard the next Japanese solar mission SOLAR-C. SUVIT has an aperture diameter of similar to 1.4 m for achieving spectro-polarimetric observations with spatial and temporal resolution exceeding the Hinode Solar Optical Telescope (SOT). We have studied structural and thermal designs of the optical telescope as well as the optical interface between the telescope and the focal plane instruments. The focal plane instruments are installed into two packages, filtergraph and spectrograph packages. The spectropolarimeter is the instrument dedicated to accurate polarimetry in the three spectrum windows at 525 nm, 854 nm, and 1083 nm for observing magnetic fields at both the photospheric and chromospheric layers. We made optical design of the spectrograph accommodating the conventional slit spectrograph and the integral field unit (IFU) for two-dimensional coverage. We are running feasibility study of the IFU using fiber arrays consisting of rectangular cores.
MISC
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Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray 2020年12月13日
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Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray 2020年12月13日
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Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray 10699 2018年7月6日© 2018 SPIE. The ASTRO-H mission was designed and developed through an international collaboration of JAXA, NASA, ESA, and the CSA. It was successfully launched on February 17, 2016, and then named Hitomi. During the in-orbit verification phase, the on-board observational instruments functioned as expected. The intricate coolant and refrigeration systems for soft X-ray spectrometer (SXS, a quantum micro-calorimeter) and soft X-ray imager (SXI, an X-ray CCD) also functioned as expected. However, on March 26, 2016, operations were prematurely terminated by a series of abnormal events and mishaps triggered by the attitude control system. These errors led to a fatal event: the loss of the solar panels on the Hitomi mission. The X-ray Astronomy Recovery Mission (or, XARM) is proposed to regain the key scientific advances anticipated by the international collaboration behind Hitomi. XARM will recover this science in the shortest time possible by focusing on one of the main science goals of Hitomi,"Resolving astrophysical problems by precise high-resolution X-ray spectroscopy".1 This decision was reached after evaluating the performance of the instruments aboard Hitomi and the mission's initial scientific results, and considering the landscape of planned international X-ray astrophysics missions in 2020's and 2030's. Hitomi opened the door to high-resolution spectroscopy in the X-ray universe. It revealed a number of discrepancies between new observational results and prior theoretical predictions. Yet, the resolution pioneered by Hitomi is also the key to answering these and other fundamental questions. The high spectral resolution realized by XARM will not offer mere refinements; rather, it will enable qualitative leaps in astrophysics and plasma physics. XARM has therefore been given a broad scientific charge: "Revealing material circulation and energy transfer in cosmic plasmas and elucidating evolution of cosmic structures and objects". To fulfill this charge, four categories of science objectives that were defined for Hitomi will also be pursued by XARM; these include (1) Structure formation of the Universe and evolution of clusters of galaxies; (2) Circulation history of baryonic matters in the Universe; (3) Transport and circulation of energy in the Universe; (4) New science with unprecedented high resolution X-ray spectroscopy. In order to achieve these scientific objectives, XARM will carry a 6 × 6 pixelized X-ray micro-calorimeter on the focal plane of an X-ray mirror assembly, and an aligned X-ray CCD camera covering the same energy band and a wider field of view. This paper introduces the science objectives, mission concept, and observing plan of XARM.
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PASJ : publications of the Astronomical Society of Japan 60(2) 275-284 2008年4月25日
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PASJ : publications of the Astronomical Society of Japan 59(3) S721-S726 2007年11月30日
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PASJ : publications of the Astronomical Society of Japan 59(3) S683-S689 2007年11月30日
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SOLAR PHYSICS 243(1) 3-17 2007年6月The Hinode satellite (formerly Solar-B) of the Japan Aerospace Exploration Agency's Institute of Space and Astronautical Science (ISAS/JAXA) was successfully launched in September 2006. As the successor to the Yohkoh mission, it aims to understand how magnetic energy gets transferred from the photosphere to the upper atmosphere and results in explosive energy releases. Hinode is an observatory style mission, with all the instruments being designed and built to work together to address the science aims. There are three instruments onboard: the Solar Optical Telescope (SOT), the EUV Imaging Spectrometer (EIS), and the X-Ray Telescope (XRT). This paper provides an overview of the mission, detailing the satellite, the scientific payload, and operations. It will conclude with discussions on how the international science community can participate in the analysis of the mission data.
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日本福祉大学情報社会科学論集 10 1-9 2007年3月30日We report on the current status of our astronomical data sonification project. This project aims to sonify astronomical data, that is, to convert a visual medium into an audio medium for both scientists and the visually impaired. We hope that sonification can lead to a new way of conceptualizing scientific data. The primary sourcesof the data used for this project come from Japanese satellites dedicated to X-ray astronomy and geophysics. This project is performed in collaboration with Nihon Fukushi University and the Center for Planning and Information Systems (PLAIN center) of the Japan Aerospace Exploration Agency (JAXA) Institute of Space andAstronautical Science (ISAS). Our project began in March 2006. Since this time we have sonified astronomical data sets, including data from X-ray pulsars, and have published these results. In this paper we also discuss future plans for the project, as well as its implications for visually impaired scientists and public.
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 54(3) 387-392 2002年6月An X-ray study was made to examine whether some part of the soft X-ray background is coming from hot gas in the Local Group. For this purpose, four consecutive pointings were made with ASCA toward a sky region between M 31 and M 33, which is close to the direction of the center of the Local Group. By comparing the X-ray surface brightness in this sky direction with that in another blank sky region near the north equatorial pole, an upper limit on any soft excess X-ray background was determined to be 2.8 x 10(-9) erg cm(-2) s(-1) sr(-1) with a 90% confidence level statistical error. Assuming an optically-thin thermal bremsstrahlung energy spectrum (Raymond-Smith model) for a temperature of 1 keV and a beta-model electron density distribution for a core radius of 100 kpc for the X-ray halo., the upper limit of the central plasma density was obtained to be 1.3 x 10(-4) cm(-3). The plasma column density is too low to contribute significantly to the observed quadrupole anisotropy in the cosmic microwave background.
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ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES 134(1) 77-102 2001年5月The X-ray emission from the central region of the Galactic plane, \l\ less than or similar to 45 degrees and \b\ less than or similar to 0.degrees4, was studied in the 0.7-10 keV energy band with a spatial resolution of similar to3' with the Advanced Satellite for Cosmology and Astrophysics (ASCA) observatory. We developed a new analysis method for the ASCA data to resolve discrete sources from the extended Galactic ridge X-ray emission (GRXE). We successfully resolved 163 discrete sources with an X-ray flux down to 10(-12.5) ergs cm(-2) s(-1) and determined the intensity variations of the GRXE as a function of the Galactic longitude with a spatial resolution of about 1 degrees. The longitudinal intensity variation in the energy band above 4 keV, for which there is little absorption in the Galactic plane, shows a large enhanced feature within \l\ less than or similar to 30 degrees. This suggests a strong enhancement ment of X-ray emissivity of the GRXE inside the 4 kpc arm of the Galaxy. Searches for identifications of the resolved X-ray sources with cataloged X-ray sources and optical stars show that the 66% are unidentified. Spectral analysis of each source shows that a large number of the unidentified sources have hard X-ray spectra obscured by the Galactic interstellar medium. We classified the sources into several groups by the flux, the hardness and the softness of the spectra, and performed further detailed analysis for the spectra summed within each group. Possible candidates of X-ray origins of these unidentified sources are discussed based on the grouping spectral analysis. Also, we derived the log N-log S relations of the resolved sources in the energy bands below and above 2 keV separately. The log N-log S relation of the Galactic X-ray sources above 2 keV was obtained for the first time with this study. It is represented by a power-law with an index of -0.79 +/- 0.07 after correction for the contribution of extragalactic X-ray sources. This flat power-law relation suggests that the spatial distribution of the X-ray sources should have an armlike structure in which the solar system is included. The integrated surface brightness of the resolved sources is about 10% of the total GRXE in both energy bands. The approximately 90% of the emission remaining is still unresolved.
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PASJ : publications of the Astronomical Society of Japan 52(5) L31-L35 2000年10月25日
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ASTRONOMISCHE NACHRICHTEN 320(4-5) 383-383 1999年
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Astronomische Nachrichten 320(4-5) 323-323 1999年 査読有り
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Publications of the Astronomical Society of Japan 49(5) L25-L30 1997年During a galactic-plane survey with ASCA in 1996 September, we detected a relatively bright, soft source at R.A. = 17h8m46.s6, DEC. = -40°9′27″ (J2000), and discovered an 11-s X-ray pulsation from the source. This source has been identified with the ROSAT source 1RXS J170849.0-400910. From a timing analysis of the source, we obtained a barycentric pulse period of P = 10.99759±0.00005 s with a broad sinusoidal shape of a pulse fraction of ∼ 30%. The energy spectrum in the 0.8-10 keV region is very soft, and can be fitted by a power-law model with a photon index of 3.5 and an absorption column density of 1.8 × 1022 cm-2. The observed pulse-phase-averaged flux in the range 0.8-10 keV is 4.3 × 10-11 erg cm-2 s-1, which corresponds to 1.7 × 10-10 erg cm-2 s-1 after correcting for soft X-ray absorption. During an observation interval of about 14 hr, neither a significant change in the pulsation period, nor a significant variation in the phase-averaged flux was detected. From these X-ray properties, we suggest that this newly discovered X-ray pulsar might be a member of a small subgroup of "anomalous" X-ray pulsars with a period close to 6-9 s.
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Publications of the Astronomical Society of Japan 48(2) 171-189 1996年 査読有りThe in-orbit performance and calibration of the Gas Imaging Spectrometer (GIS), located on the focal plane of the X-ray astronomy satellite ASCA, are described. An extensive in-orbit calibration has confirmed its basic performance, including a position resolution of 0.6 mm (FWHM) and an energy resolution of 7.8% (FWHM), both at 6 keV. When combined with the X-ray telescope, the GIS sensitivity range becomes 0.7-10 keV. The in-orbit non X-ray background of the GIS has been confirmed to be as low as (5-9) × 10-4 c s-1 cm-2 keV-1 over the 1-10 keV range. The long-term detector gain has been stable within a few % for nearly 3 years. Extensive observations of the Crab Nebula and other sources have provided accurate calibrations of the position response, photometric capability, dead time, and timing accuracy of the GIS. Furthermore, the overall energy response, including the temporal and positional gain variations and the absolute gain scale, has been calibrated to ∼ 1%. Thus, the GIS is working as an all-round cosmic X-ray detector, capable of X-ray imagery, fine X-ray spectroscopy, X-ray photometry with a flux dynamic range covering more than 5 orders of magnitude, and fast X-ray photometry with a time resolution up to 60 μs.
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Proceedings of SPIE - The International Society for Optical Engineering 2518 85-95 1995年 査読有りThe ASTRO-E satellite is scheduled for launch in 2000 by the Institute of Space and Astronautical Science (ISAS). In this paper the design and performance of the hard x ray detector (HXD) developed for ASTRO-E are described. The HXD is a combination of YAP/BGO phoswich scintillators and silicon PIN diodes covering a wide energy band of 10 - 700 keV. The detector background is reduced down to several times 10 -6c/s/cm 2/keV, and the sensitivity of the HXD is more than one order of magnitude higher than any other past missions in the range of a few 10 keV to several 100 keV. Thus ASTRO-E HXD is expected to achieve an extreme high performance for detecting cosmic hard x rays and low-energy gamma rays. Astrophysics to be explored with the HXT are expected to be extremely widespread and rich.
主要な講演・口頭発表等
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第67回宇宙科学技術連合講演会 2023年10月19日 日本航空宇宙学会This paper shows the system design and development status of the data handling system, ISC(DH), for the Martian Moons eXploration (MMX) mission. ISC(DH) consists of SMU (Spacecraft Management Unit), MDP (Mission Data Processor) and PDCU (Power Distribution Control Unit). System overviews and configuration are described.
共同研究・競争的資金等の研究課題
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日本学術振興会 科学研究費助成事業 2007年 - 2009年
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日本学術振興会 科学研究費助成事業 2004年 - 2005年
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日本学術振興会 科学研究費助成事業 2002年 - 2004年
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日本学術振興会 科学研究費助成事業 2002年 - 2002年
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日本学術振興会 科学研究費助成事業 2000年 - 2001年
