研究者業績

藤本 龍一

フジモト リュウイチ  (Ryuichi Fujimoto)

基本情報

所属
国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 宇宙物理学研究系 教授
総合研究大学院大学 先端学術院 宇宙科学コース 教授
東京科学大学 理学院 物理学系 特定教授
北海道大学 大学院理学院 宇宙理学専攻 客員教授
学位
博士(理学)(東京大学)
修士(東京大学)

研究者番号
20280555
ORCID ID
 https://orcid.org/0000-0002-2374-7073
J-GLOBAL ID
200901095989600566
researchmap会員ID
1000363020

X線マイクロカロリメータを用いた極低温精密X線分光装置の開発に取り組み,2023年9月打ち上げのXRISM衛星に搭載されたResolve観測装置として実現しました.

研究指導のテーマとしては,(1) XRISM衛星による精密X線分光観測データを解析し,銀河団ガスの運動を調べて,宇宙の大規模構造形成過程の理解を深める,(2) 宇宙マイクロ波背景放射の偏光観測を目指すLiteBIRD衛星を見据えた実験的研究を行なう等.特定の自然現象について理解を深めると同時に,複雑な自然現象の背景にある物理法則に至る過程を,実験・解析手法とともにしっかりと身につけてもらいたいと考えています.


学歴

 2

委員歴

 1

論文

 170
  • KC Gendreau, MD Audley, KA Arnaud, KR Boyce, R Fujimoto, Y Ishisaki, RL Kelley, T Mihara, K Mitsuda, FS Porter, CK Stahle, AE Szymkowiak
    EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X 3765 137-147 1999年  査読有り
    XRS is the microcalorimeter X-ray detector aboard the US-Japanese ASTRO-E observatory, which is scheduled to be launched in early 2000. XRS is a high resolution spectrometer- with less than 9 eV resolution at 3 keV and better than 14 eV resolution over its bandpass ranging from about 0.3 keV to 15 keV. Here we present the results of our first calibration of the XRS instrument. We describe the methods used to extract detailed information about the detection efficiency and spectral redistribution of the instrument. We also present comparisons of simulations and real data to test our detector models.
  • MD Audley, KA Arnaud, KC Gendreau, KR Boyce, CM Fleetwood, RL Kelley, RA Keski-Kuha, FS Porter, CK Stahle, AE Szymkowiak, JL Tveekrem, R Fujimoto, K Mitsuda, Y Ishisaki, T Mihara
    EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X 3765 751-761 1999年  査読有り
    We describe the transmission calibration of the Astro-E XRS blocking filters. The XRS instrument has five aluminized polymide blocking filters. These filters are located at thermal stages ranging from 200 K to 60 mK. They are each about 1000 Angstrom thick. XRS will have high energy resolution which will enable it to see some of the extended fine structure around the oxygen and aluminum K edges of these filters. Thus, we are conducting a high spectral resolution calibration of the filters near these energies to resolve out extended fine structure and absorption lines.
  • RL Kelley, MD Audley, KR Boyce, Breon, SR, R Fujimoto, KC Gendreau, SS Holt, Y Ishisaki, D McCammon, T Mihara, K Mitsuda, SH Moseley, DB Mott, FS Porter, CK Stahle, AE Szymkowiak
    EUV, X-RAY, AND GAMMA-RAY INSTRUMENTATION FOR ASTRONOMY X 3765 114-127 1999年  査読有り
    The Astro-E High Resolution X-ray Spectrometer (XRS) was developed jointly by the NASA/Goddard Space Flight Center and the Institute of Space and Astronautical Science in Japan. The instrument is based on a new approach to spectroscopy, the X-ray microcalorimeter. This device senses the energies of individual X-ray photons as heat with extreme precision. A 32 channel array of microcalorimeters is being employed, each with an energy resolution of about 12 eV at 6 keV (the Fe-K region). This will provide spectral resolving power 10 times higher than any other non;dispersive X-ray spectrometer. The instrument incorporates a three stage cooling system capable of operating the array at 60 mK for about two years in orbit. The array sits at the focus of a grazing incidence conical mirror. The quantum efficiency of the microcalorimeters and the reflectivity of the X-ray mirror system combine to give high throughput over the 0.3-12 keV energy band. This new capability will enable the study of a wide range of high-energy astrophysical sources with unprecedented spectral sensitivity. This paper presents the basic design requirements and implementation of the XRS, and also describes the instrument parameters and performance.
  • Nakagawa, T., Kii, T., Fujimoto, R., Miyazaki, T., Inoue, H., Ogasaka, Y., Ikebe, Y., Kawabe, R.
    Astronomische Nachrichten 320(4-5) 246-247 1999年  
    We made a series of ASCA observations of Ultra Luminous Infrared Galaxies (ULIRGs), to reveal the origin of their luminosities and to test a proposed evolutionary scenario of ULIRGs. We discovered embedded AGN in some galaxies, but the relative contribution of AGN activity to the total luminosity varies significantly from galaxy to galaxy and has no correlation with the evolutionary sequence as mergers.
  • Mitsuda, K., Fujimoto, R., Miyazaki, T., Maegami, K., Aruga, Y., Oshima, T., Nakayama, S., Shoji, S., Kudo, H., Yokoyama, Y., Mihara, T., Shimizu, H.M.
    Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 436(1-2) 252-255 1999年  
    We propose a new method to readout signals from a TES (superconducting Transition-Edge Sensor) calorimeter array with a single or a small number of SQUIDs, Since phonon noise and Johnson noise of a calorimeter can be made very small in these calorimeters, an increase in noise, thus a degradation of energy resolution by adding signals from plural pixels together at some stage of signal processing may be acceptable for some applications of TES calorimeters. We propose to use a SQUID with multi-input coils which will sense signals from different pixels. The input coils of a SQUID are electrically well-isolated from each other. The pixel that generates a signal can be identified by utilizing additional information, such as the pulse shape. We studied the feasibility of this method with analysis and simulations, and show for example, that a 16 x 16 pixel array can be read out with 16 SQUIDs. (C) 1999 Elsevier Science B.V. All rights reserved.
  • Nagayama, Y., Itoh, M., Mitsuda, K., Fujimoto, R., Okada, K.
    Astronomische Nachrichten 320(4-5) 303-303 1999年  
  • Nakagawa, T., Kii, T., Fujimoto, R., Miyazaki, T., Inoue, H., Ogasaka, Y., Kawabe, R.
    Astrophysics and Space Science 266(1-2) 43-48 1999年  
  • Ishida, M., Fujimoto, R.
    Astronomische Nachrichten 320(4-5) 352-352 1999年  
  • T Murakami, Y Ueda, R Shibata, R Fujimoto, M Ishida, S Uno, F Nagase, A Yoshida, N Kawai, F Tokanai, C Otani, M Namiki, J van Paradijs, Y Tanaka, J Greiner, T Takeshima, FE Marshall, RHD Corbet, JK Cannizzo, A Valinia, JH Swank, SD Barthelmy, CR Robinson, C Kouveliotou, Connaughton, V, RM Kippen, G Pendleton, DA Smith, AM Levine, RA Remillard, RK Vanderspek, K Hurley, L Piro, E Costa, F Fiore, J Heise
    GAMMA-RAY BURSTS, PTS 1 AND 2 (428) 435-440 1998年  査読有り
    ASCA has made observations of the fields of six gamma-ray bursts after detections by BeppoSAX and RXTE. We summarize these observations.
  • Terashima, Y., Ptak, A., Fujimoto, R., Iyoh, M., Kunieda, H., Makishima, K., Serlemitsos, P.J.
    Astrophysical Journal 496(1 PART I) 1998年  
  • Urry, C.M., Treves, A., Maraschi, L., Marshall, H.L., Kii, T., Madejski, G., Penton, S., Pesce, J.E., Pian, E., Celotti, A., Fujimoto, R., Making, F., Otani, C., Sambruna, R.M., Sasaki, K., Shull, J.M., Smith, P.S., Takahashi, T., Tashiro, M.
    Astrophysical Journal 486(2 PART I) 1997年  
  • Br, t, W.N., Fabian, A.C., Takahashi, K., Fujimoto, R., Yamashita, A., Inoue, H., Ogasaka, Y.
    Monthly Notices of the Royal Astronomical Society 290(4) 1997年  
  • Ishida, M., Matsuzaki, K., Fujimoto, R., Mukai, K., Osborne, J.P.
    Monthly Notices of the Royal Astronomical Society 287(3) 1997年  
  • Fujimoto, R., Ishida, M.
    Astrophysical Journal 474(2 PART I) 1997年  
  • Ogasaka, Y., Inoue, H., Brandt, W.N., Fabian, A.C., Kii, T., Nakagawa, T., Fujimoto, R., Otani, C.
    Publications of the Astronomical Society of Japan 49(2) 179-185 1997年  
    We report on ASCA observations of two ultraluminous far-infrared galaxies, IRAS 15307+3252 and IRAS 20460+1925. An X-ray flux of 1.53 × 10 erg cm s in the 2-10 keV band was detected from IRAS 20460+1925. The continuous spectrum is well represented by a power law with a photon index of 1.99 and excess photoelectric absorption by a column of (2.6 ) × 10 cm in the rest frame. The spectrum also shows an iron K emission line with an equivalent width of 260 eV and a centroid energy of 6.36±0.08 keV in the rest frame. These spectral properties are consistent with those of Seyfert-2 galaxies, although the intrinsic 2-10 keV X-ray luminosity (corrected for absorption) of 1.20 × 10 erg s is high and close to that of quasars. No X-rays were detected from IRAS 15307+3252, and the upper limit to the X-ray flux is 7.2 × 10 erg cm s in the 2-10 keV band. However, the upper limit on the ratio of the X-ray flux to the far-infrared flux is not inconsistent with a source containing a highly obscured quasar. -12 -2 -1 +0.18 +0.29 22 -2 +145 44 -1 -14 -2 -1 -0.15 -0.32 -137
  • Hellier, C., Mukai, K., Ishida, M., Fujimoto, R.
    Monthly Notices of the Royal Astronomical Society 280(3) 1996年  
  • Hartman, R.C., Webb, J.R., Marscher, A.P., Travis, J.P., Dermer, C.D., Aller, H.D., Aller, M.F., Balonek, T.J., Bennett, K., Bloom, S.D., Fujimoto, R., Hermsen, W., Hughes, P., Jenkins, P., Kii, T., Kurfess, J.D., Making, F., Mattox, J.R., Von Montigny, C., Ohashi, T., Robson, I., Rvan, J., Sadun, A., Sch{\"o}nfelder, V., Smith, A.G., Ter{\"a}sranta, H., Tornikoski, M., Turner, M.J.L.
    Astrophysical Journal 461(2 PART I) 1996年  
  • Webb, J.R., Shrader, C.R., Balonek, T.J., Crenshaw, D.M., Kazanas, D., Clements, S., Smith, A.G., Nair, A.D., Leacock, R.J., Gombola, P.P., Sadun, A., Miller, H.R., Robson, I., Fujimoto, R., Makino, F., Kii, T., Aller, H., Aller, M., Hughes, P., Valtaoja, E., Ter{\"a}sranta, H., Salonen, E., Tornikoski, M., Chism, W.
    Astrophysical Journal 422(2) 1994年  
  • Mitsui T, Fujimoto R, Ishisaki Y, Ueda Y, Yamazaki Y, Asai S, Orito S
    Physical review letters 70(15) 2265-2268 1993年4月  査読有り
  • Yoshida, K, K.Mitsuda, K, K.Ebisawa, K, U.Ueda, U, R.Fujimoto, R, T.Yagoob, T, C.Done, C
    Publ.Astron.Soc.Japan 45(4) 605-616 1993年  査読有り

MISC

 131
  • 佐藤浩介, 大橋隆哉, 石崎欣尚, 江副祐一郎, 山田真也, 山崎典子, 満田和久, 石田学, 前田良知, 田原譲, 三石郁之, 藤本龍一, 鶴剛, 太田直美, 大里健, 中島真也
    日本天文学会年会講演予稿集 2018 225 2018年8月20日  
  • 江副祐一郎, 石崎欣尚, 藤本龍一, 竹井洋, 石川久美, 安田進, 柳瀬慶一, 山崎典子, 佐藤浩介, 北本俊二, 小山志勇, 野田博文, 吉田誠至, 金尾憲一, 恒松正二, KELLEY R. L., KILBOURNE C. A., DIPIRRO M. J., SHIRRON P.
    日本天文学会年会講演予稿集 2018 2018年  
  • Alle, S.W., Aharonian, F., Akamatsu, H., Akimoto, F., Allen, S.W., Angelini, L., Audard, M., Awaki, H., Axelsson, M., Bamba, A., Bautz, M.W., Blandford, R., Brenneman, L.W., Brown, G.V., Bulbul, E., Cackett, E.M., Chernyakova, M., Chiao, M.P., Coppi, P.S., Costantini, E., De Plaa, J., De Vries, C.P., Den Herder, J.-W., Done, C., Dotani, T., Ebisawa, K., Eckart, M.E., Enoto, T., Ezoe, Y., Fabian, A.C., Ferrigno, C., Foster, A.R., Fujimoto, R., Fukazawa, Y., Furuzawa, A., Galeazzi, M., Gallo, L.C., Gandhi, P., Giustini, M., Goldwurm, A., Gu, L., Guainazzi, M., Haba, Y., Hagino, K., Hamaguchi, K., Harrus, I.M., Hatsukade, I., Hayashi, K., Hayashi, T., Hayashida, K., Hiraga, J.S., Hornschemeier, A., Hoshino, A., Hughes, J.P., Ichinohe, Y., Iizuka, R., Inoue, H., Inoue, Y., Ishida, M., Ishikawa, K., Ishisaki, Y., Iwai, M., Kaastra, J., Kallman, T., Kamae, T., Kataoka, J., Katsuda, S., Kawai, N., Kelley, R.L., Kilbourne, C.A., Kitaguchi, T., Kitamoto, S., Kitayama, T., Kohmura, T., Kokubun, M., Koyama, K., Koyama, S., Kretschmar, P., Krimm, H.A., Kubota, A., Kunieda, H., Laurent, P., Lee, S.-H., Leutenegger, M.A., Limousin, O.O., Loewenstein, M., Long, K.S., Lumb, D., Madejski, G., Maeda, Y., Maier, D., Makishima, K., Markevitch, M., Matsumoto, H., Matsushita, K., Mccammon, D., Mcnamara, B.R., Mehdipour, M., Miller, E.D., Miller, J.M., Mineshige, S., Mitsuda, K., Mitsuishi, I., Miyazawa, T., Mizuno, T., Mori, H., Mori, K., Mukai, K., Murakami, H., Mushotzky, R.F., Nakagawa, T., Nakajima, H., Nakamori, T., Nakashima, S., Nakazawa, K., Nobukawa, K.K., Nobukawa, M., Noda, H., Odaka, H., Ohashi, T., Ohno, M., Okajima, T., Ota, N., Ozaki, M., Paerels, F., Paltani, S., Petre, R., Pinto, C., Porter, F.S., Pottschmidt, K., Reynolds, C.S., Safi-Harb, S., Saito, S., Sakai, K., Sasaki, T., Sato, G., Sato, K., Sato, R., Sawada, M., Schartel, N., Serlemtsos, P.J., Seta, H., Shidatsu, M., Simionescu, A., Smith, R.K., Soong, Y., Stawarz, Ł., Sugawara, Y., Sugita, S., Szymkowiak, A., Tajima, H., Takahashi, H., Takahashi, T., Takeda, S., Takei, Y., Tamagawa, T., Tamura, T., Tanaka, T., Tanaka, Y., Tanaka, Y.T., Tashiro, M.S., Tawara, Y., Terada, Y., Terashima, Y., Tombesi, F., Tomida, H., Tsuboi, Y., Tsujimoto, M., Tsunemi, H., Suru, T.G., Uchida, H., Uchiyama, H., Uchiyama, Y., Ueda, S., Ueda, Y., Uno, S., Urry, C.M., Ursino, E., Watanabe, S., Werner, N., Wilkins, D.R., Williams, B.J., Yamada, S., Yamaguchi, H., Yamaoka, K., Yamasaki, N.Y., Yamauchi, M., Yamauchi, S., Yaqoob, T., Yatsu, Y., Yonetoku, D., Zhuravleva, I., Zoghbi, A., Nakaniwa, N.
    Publications of the Astronomical Society of Japan 70(2) 2018年  
    We report a Hitomi observation of IGR J16318-4848, a high-mass X-ray binary<br /> system with an extremely strong absorption of N_H~10^{24} cm^{-2}. Previous<br /> X-ray studies revealed that its spectrum is dominated by strong fluorescence<br /> lines of Fe as well as continuum emission. For physical and geometrical insight<br /> into the nature of the reprocessing material, we utilize the high spectroscopic<br /> resolving power of the X-ray microcalorimeter (the soft X-ray spectrometer;<br /> SXS) and the wide-band sensitivity by the soft and hard X-ray imager (SXI and<br /> HXI) aboard Hitomi. Even though photon counts are limited due to unintended<br /> off-axis pointing, the SXS spectrum resolves Fe K{\alpha_1} and K{\alpha_2}<br /> lines and puts strong constraints on the line centroid and width. The line<br /> width corresponds to the velocity of 160^{+300}_{-70} km s^{-1}. This<br /> represents the most accurate, and smallest, width measurement of this line made<br /> so far from any X-ray binary, much less than the Doppler broadening and shift<br /> expected from speeds which are characteristic of similar systems. Combined with<br /> the K-shell edge energy measured by the SXI and HXI spectra, the ionization<br /> state of Fe is estimated to be in the range of Fe I--IV. Considering the<br /> estimated ionization parameter and the distance between the X-ray source and<br /> the absorber, the density and thickness of the materials are estimated. The<br /> extraordinarily strong absorption and the absence of a Compton shoulder<br /> component is confirmed. These characteristics suggest reprocessing materials<br /> which are distributed in a narrow solid angle or scattering primarily with warm<br /> free electrons or neutral hydrogen.
  • Aharonian, F., Akamatsu, H., Akimoto, F., Allen, S.W., Angelini, L., Audard, M., Awaki, H., Axelsson, M., Bamba, A., Bautz, M.W., Blandford, R., Brenneman, L.W., Brown, G.V., Bulbul, E., Cackett, E.M., Chernyakova, M., Chiao, M.P., Coppi, P.S., Costantini, E., De Plaa, J., De Vries, C.P., Den Herder, J.-W., Done, C., Dotani, T., Ebisawa, K., Eckart, M.E., Enoto, T., Ezoe, Y., Fabian, A.C., Ferrigno, C., Foster, A.R., Fujimoto, R., Fukazawa, Y., Furuzawa, A., Galeazzi, M., Gallo, L.C., Gandhi, P., Giustini, M., Goldwurm, A., Gu, L., Guainazzi, M., Haba, Y., Hagino, K., Hamaguchi, K., Harrus, I.M., Hatsukade, I., Hayashi, K., Hayashi, T., Hayashida, K., Hiraga, J.S., Hornschemeier, A., Hoshino, A., Hughes, J.P., Ichinohe, Y., Iizuka, R., Inoue, H., Inoue, Y., Ishida, M., Ishikawa, K., Ishisaki, Y., Iwai, M., Kaastra, J., Kallman, T., Kamae, T., Kataoka, J., Katsuda, S., Kawai, N., Kelley, R.L., Kilbourne, C.A., Kitaguchi, T., Kitamoto, S., Kitayama, T., Kohmura, T., Kokubun, M., Koyama, K., Koyama, S., Kretschmar, P., Krimm, H.A., Kubota, A., Kunieda, H., Laurent, P., Lee, S.-H., Leutenegger, M.A., Limousin, O., Loewenstein, M., Long, K.S., Lumb, D., Madejski, G., Maeda, Y., Maier, D., Makishima, K., Markevitch, M., Matsumoto, H., Matsushita, K., McCammon, D., McNamara, B.R., Mehdipour, M., Miller, E.D., Miller, J.M., Mineshige, S., Mitsuda, K., Mitsuishi, I., Miyazawa, T., Mizuno, T., Mori, H., Mori, K., Mukai, K., Murakami, H., Mushotzky, R.F., Nakagawa, T., Nakajima, H., Nakamori, T., Nakashima, S., Nakazawa, K., Nobukawa, K.K., Nobukawa, M., Noda, H., Odaka, H., Ohashi, T., Ohno, M., Okajima, T., Ota, N., Ozaki, M., Paerels, F., Paltani, S., Petre, R., Pinto, C., Porter, F.S., Pottschmidt, K., Reynolds, C.S., Safi-Harb, S., Saito, S., Sakai, K., Sasaki, T., Sato, G., Sato, K., Sato, R., Sawada, M., Schartel, N., Serlemtsos, P.J., Seta, H., Shidatsu, M., Simionescu, A., Smith, R.K., Soong, Y., Stawarz, L., Sugawara, Y., Sugita, S., Szymkowiak, A., Tajima, H., Takahashi, H., Takahashi, T., Takeda, S., Takei, Y., Tamagawa, T., Tamura, T., Tanaka, T., Tanaka, Y., Tanaka, Y.T., Tashiro, M.S., Tawara, Y., Terada, Y., Terashima, Y., Tombesi, F., Tomida, H., Tsuboi, Y., Tsujimoto, M., Tsunemi, H., Tsuru, T.G., Uchida, H., Uchiyama, H., Uchiyama, Y., Ueda, S., Ueda, Y., Uno, S., Urry, C.M., Ursino, E., Watanabe, S., Werner, N., Wilkins, D.R., Williams, B.J., Yamada, S., Yamaguchi, H., Yamaoka, K., Yamasaki, N.Y., Yamauchi, M., Yamauchi, S., Yaqoob, T., Yatsu, Y., Yonetoku, D., Zhuravleva, I., Zoghbi, A., Uchida, Y.
    Publications of the Astronomical Society of Japan 70(6) 2018年  
    We present the results from the Hitomi Soft Gamma-ray Detector (SGD)<br /> observation of the Crab nebula. The main part of SGD is a Compton camera, which<br /> in addition to being a spectrometer, is capable of measuring polarization of<br /> gamma-ray photons. The Crab nebula is one of the brightest X-ray / gamma-ray<br /> sources on the sky, and, the only source from which polarized X-ray photons<br /> have been detected. SGD observed the Crab nebula during the initial test<br /> observation phase of Hitomi. We performed the data analysis of the SGD<br /> observation, the SGD background estimation and the SGD Monte Carlo simulations,<br /> and, successfully detected polarized gamma-ray emission from the Crab nebula<br /> with only about 5 ks exposure time. The obtained polarization fraction of the<br /> phase-integrated Crab emission (sum of pulsar and nebula emissions) is (22.1<br /> $\pm$ 10.6)% and, the polarization angle is 110.7$^o$ + 13.2 / $-$13.0$^o$ in<br /> the energy range of 60--160 keV (The errors correspond to the 1 sigma<br /> deviation). The confidence level of the polarization detection was 99.3%. The<br /> polarization angle measured by SGD is about one sigma deviation with the<br /> projected spin axis of the pulsar, 124.0$^o$ $\pm$0.1$^o$.
  • Aharonian, F., Akamatsu, H., Akimoto, F., Allen, S.W., Angelini, L., Audard, M., Awaki, H., Axelsson, M., Bamba, A., Bautz, M.W., Blandford, R., Brenneman, L.W., Brown, G.V., Bulbul, E., Cackett, E.M., Chernyakova, M., Chiao, M.P., Coppi, P.S., Costantini, E., De Plaa, J., De Vries, C.P., Den Herder, J.-W., Done, C., Dotani, T., Ebisawa, K., Eckart, M.E., Enoto, T., Ezoe, Y., Fabian, A.C., Ferrigno, C., Foster, A.R., Fujimoto, R., Fukazawa, Y., Furukawa, M., Furuzawa, A., Galeazzi, M., Gallo, L.C., Gandhi, P., Giustini, M., Goldwurm, A., Gu, L., Guainazzi, M., Haba, Y., Hagino, K., Hamaguchi, K., Harrus, I.M., Hatsukade, I., Hayashi, K., Hayashi, T., Hayashida, K., Hiraga, J.S., Hornschemeier, A., Hoshino, A., Hughes, J.P., Ichinohe, Y., Iizuka, R., Inoue, H., Inoue, Y., Ishida, M., Ishikawa, K., Ishisaki, Y., Iwai, M., Kaastra, J., Kallman, T., Kamae, T., Kataoka, J., Kato, Y., Katsuda, S., Kawai, N., Kelley, R.L., Kilbourne, C.A., Kitaguchi, T., Kitamoto, S., Kitayama, T., Kohmura, T., Kokubun, M., Koyama, K., Koyama, S., Kretschmar, P., Krimm, H.A., Kubota, A., Kunieda, H., Laurent, P., Lee, S.-H., Leutenegger, M.A., Limousin, O., Loewenstein, M., Long, K.S., Lumb, D., Madejski, G., Maeda, Y., Maier, D., Makishima, K., Markevitch, M., Matsumoto, H., Matsushita, K., McCammon, D., McNamara, B.R., Mehdipour, M., Miller, E.D., Miller, J.M., Mineshige, S., Mitsuda, K., Mitsuishi, I., Miyazawa, T., Mizuno, T., Mori, H., Mori, K., Mukai, K., Murakami, H., Mushotzky, R.F., Nakagawa, T., Nakajima, H., Nakamori, T., Nakashima, S., Nakazawa, K., Nobukawa, K.K., Nobukawa, M., Noda, H., Odaka, H., Ohashi, T., Ohno, M., Okajima, T., Ota, N., Ozaki, M., Paerels, F., Paltani, S., Petre, R., Pinto, C., Porter, F.S., Pottschmidt, K., Reynolds, C.S., Safi-Harb, S., Saito, S., Sakai, K., Sasaki, T., Sato, G., Sato, K., Sato, R., Sawada, M., Schartel, N., Serlemtsos, P.J., Seta, H., Shidatsu, M., Simionescu, A., Smith, R.K., Soong, Y., Stawarz, Ł., Sugawara, Y., Sugita, S., Szymkowiak, A., Tajima, H., Takahashi, H., Takahashi, T., Takeda, S., Takei, Y., Tamagawa, T., Tamura, T., Tanaka, T., Tanaka, Y., Tanaka, Y.T., Tashiro, M.S., Tawara, Y., Terada, Y., Terashima, Y., Tombesi, F., Tomida, H., Tsuboi, Y., Tsujimoto, M., Tsunemi, H., Tsuru, T.G., Uchida, H., Uchiyama, H., Uchiyama, Y., Ueda, S., Ueda, Y., Uno, S., Urry, C.M., Ursino, E., Watanabe, S., Werner, N., Wilkins, D.R., Williams, B.J., Yamada, S., Yamaguchi, H., Yamaoka, K., Yamasaki, N.Y., Yamauchi, M., Yamauchi, S., Yaqoob, T., Yatsu, Y., Yonetoku, D., Zhuravleva, I., Zoghbi, A.
    Publications of the Astronomical Society of Japan 70(2) 2018年  
    The present paper investigates the temperature structure of the X-ray<br /> emitting plasma in the core of the Perseus cluster using the 1.8--20.0 keV data<br /> obtained with the Soft X-ray Spectrometer (SXS) onboard the Hitomi Observatory.<br /> A series of four observations were carried out, with a total effective exposure<br /> time of 338 ks and covering a central region $\sim7&#039;$ in diameter. The SXS was<br /> operated with an energy resolution of $\sim$5 eV (full width at half maximum)<br /> at 5.9 keV. Not only fine structures of K-shell lines in He-like ions but also<br /> transitions from higher principal quantum numbers are clearly resolved from Si<br /> through Fe. This enables us to perform temperature diagnostics using the line<br /> ratios of Si, S, Ar, Ca, and Fe, and to provide the first direct measurement of<br /> the excitation temperature and ionization temperature in the Perseus cluster.<br /> The observed spectrum is roughly reproduced by a single temperature thermal<br /> plasma model in collisional ionization equilibrium, but detailed line ratio<br /> diagnostics reveal slight deviations from this approximation. In particular,<br /> the data exhibit an apparent trend of increasing ionization temperature with<br /> increasing atomic mass, as well as small differences between the ionization and<br /> excitation temperatures for Fe, the only element for which both temperatures<br /> can be measured. The best-fit two-temperature models suggest a combination of 3<br /> and 5 keV gas, which is consistent with the idea that the observed small<br /> deviations from a single temperature approximation are due to the effects of<br /> projection of the known radial temperature gradient in the cluster core along<br /> the line of sight. Comparison with the Chandra/ACIS and the XMM-Newton/RGS<br /> results on the other hand suggests that additional lower-temperature components<br /> are present in the ICM but not detectable by Hitomi SXS given its 1.8--20 keV<br /> energy band.

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