研究者業績

福島 光太郎

フクシマ コウタロウ  (Kotaro Fukushima)

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 宇宙航空プロジェクト研究員
(兼任)宇宙科学研究所 X線分光撮像衛星(XRISM)プロジェクトチーム 宇宙航空プロジェクト研究員

研究者番号
51003595
ORCID ID
 https://orcid.org/0000-0001-8055-7113
J-GLOBAL ID
202401002152895362
Researcher ID
JPK-5103-2023
researchmap会員ID
R000066682

論文

 30
  • Marc Audard, Hisamitsu Awaki, Ralf Ballhausen, Aya Bamba, Ehud Behar, Rozenn Boissay-Malaquin, Laura Brenneman, Gregory V Brown, Lia Corrales, Elisa Costantini, Renata Cumbee, Maria Diaz-Trigo, Chris Done, Tadayasu Dotani, Ken Ebisawa, Megan Eckart, Dominique Eckert, Teruaki Enoto, Satoshi Eguchi, Yuichiro Ezoe, Adam Foster, Ryuichi Fujimoto, Yutaka Fujita, Yasushi Fukazawa, Kotaro Fukushima, Akihiro Furuzawa, Luigi Gallo, Javier A García, Liyi Gu, Matteo Guainazzi, Kouichi Hagino, Kenji Hamaguchi, Isamu Hatsukade, Katsuhiro Hayashi, Takayuki Hayashi, Natalie Hell, Edmund Hodges-Kluck, Ann Hornschemeier, Yuto Ichinohe, Manabu Ishida, Kumi Ishikawa, Yoshitaka Ishisaki, Jelle Kaastra, Timothy Kallman, Erin Kara, Satoru Katsuda, Yoshiaki Kanemaru, Richard Kelley, Caroline Kilbourne, Shunji Kitamoto, Shogo Kobayashi, Takayoshi Kohmura, Aya Kubota, Maurice Leutenegger, Michael Loewenstein, Yoshitomo Maeda, Maxim Markevitch, Hironori Matsumoto, Kyoko Matsushita, Dan McCammon, Brian McNamara, François Mernier, Eric D Miller, Jon M Miller, Ikuyuki Mitsuishi, Misaki Mizumoto, Tsunefumi Mizuno, Koji Mori, Koji Mukai, Hiroshi Murakami, Richard Mushotzky, Hiroshi Nakajima, Kazuhiro Nakazawa, Jan-Uwe Ness, Kumiko Nobukawa, Masayoshi Nobukawa, Hirofumi Noda, Hirokazu Odaka, Shoji Ogawa, Anna Ogorzalek, Takashi Okajima, Naomi Ota, Stephane Paltani, Robert Petre, Paul Plucinsky, Frederick Scott Porter, Katja Pottschmidt, Kosuke Sato, Toshiki Sato, Makoto Sawada, Hiromi Seta, Megumi Shidatsu, Aurora Simionescu, Randall Smith, Hiromasa Suzuki, Andrew Szymkowiak, Hiromitsu Takahashi, Mai Takeo, Toru Tamagawa, Keisuke Tamura, Takaaki Tanaka, Atsushi Tanimoto, Makoto Tashiro, Yukikatsu Terada, Yuichi Terashima, Yohko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi G Tsuru, Hiroyuki Uchida, Nagomi Uchida, Yuusuke Uchida, Hideki Uchiyama, Yoshihiro Ueda, Shinichiro Uno, Jacco Vink, Shin Watanabe, Brian J Williams, Satoshi Yamada, Shinya Yamada, Hiroya Yamaguchi, Kazutaka Yamaoka, Noriko Yamasaki, Makoto Yamauchi, Shigeo Yamauchi, Tahir Yaqoob, Tomokage Yoneyama, Tessei Yoshida, Mihoko Yukita, Irina Zhuravleva, Q Daniel Wang, Yuki Amano, Kojiro Tanaka, Takuto Narita, Yuken Ohshiro, Anje Yoshimoto, Yuma Aoki, Mayura Balakrishnan
    Publications of the Astronomical Society of Japan 2024年12月26日  査読有り
    Abstract Sagittarius A East is a supernova remnant with a unique surrounding environment, as it is located in the immediate vicinity of the supermassive black hole at the Galactic center, Sagittarius A$^{*}$. The X-ray emission of the remnant is suspected to show features of overionized plasma, which would require peculiar evolutionary paths. We report on the first observation of Sagittarius A East with the X-Ray Imaging and Spectroscopy Mission (XRISM). Equipped with a combination of a high-resolution microcalorimeter spectrometer and a large field-of-view CCD imager, we for the first time resolved the Fe xxv K-shell lines into fine structure lines and measured the forbidden-to-resonance intensity ratio to be $1.39 \pm 0.12$, which strongly suggests the presence of overionized plasma. We obtained a reliable constraint on the ionization temperature just before the transition into the overionization state, of $\gt\! 4\:$keV. The recombination timescale was constrained to be $\lt\! 8 \times 10^{11} \:$cm$^{-3}\:$s. The small velocity dispersion of $109 \pm 6\:$km$\:$s$^{-1}$ indicates a low Fe ion temperature $\lt\! 8\:$keV and a small expansion velocity $\lt\! 200\:$km$\:$s$^{-1}$. The high initial ionization temperature and small recombination timescale suggest that either rapid cooling of the plasma via adiabatic expansion from dense circumstellar material or intense photoionization by Sagittarius A$^{*}$ in the past may have triggered the overionization.
  • Marc Audard, Hisamitsu Awaki, Ralf Ballhausen, Aya Bamba, Ehud Behar, Rozenn Boissay-Malaquin, Laura Brenneman, Gregory V. Brown, Lia Corrales, Elisa Costantini, Renata Cumbee, María Díaz Trigo, Chris Done, Tadayasu Dotani, Ken Ebisawa, Megan E. Eckart, Dominique Eckert, Satoshi Eguchi, Teruaki Enoto, Yuichiro Ezoe, Adam Foster, Ryuichi Fujimoto, Yutaka Fujita, Yasushi Fukazawa, Kotaro Fukushima, Akihiro Furuzawa, Luigi Gallo, Javier A. García, Liyi Gu, Matteo Guainazzi, Kouichi Hagino, Kenji Hamaguchi, Isamu Hatsukade, Katsuhiro Hayashi, Takayuki Hayashi, Natalie Hell, Edmund Hodges-Kluck, Ann Hornschemeier, Yuto Ichinohe, Manabu Ishida, Kumi Ishikawa, Yoshitaka Ishisaki, Jelle Kaastra, Timothy Kallman, Erin Kara, Satoru Katsuda, Yoshiaki Kanemaru, Richard Kelley, Caroline Kilbourne, Shunji Kitamoto, Shogo Kobayashi, Takayoshi Kohmura, Aya Kubota, Maurice Leutenegger, Michael Loewenstein, Yoshitomo Maeda, Maxim Markevitch, Hironori Matsumoto, Kyoko Matsushita, Dan McCammon, Brian McNamara, François Mernier, Eric D. Miller, Jon M. Miller, Ikuyuki Mitsuishi, Misaki Mizumoto, Tsunefumi Mizuno, Koji Mori, Koji Mukai, Hiroshi Murakami, Richard Mushotzky, Hiroshi Nakajima, Kazuhiro Nakazawa, Jan-Uwe Ness, Kumiko Nobukawa, Masayoshi Nobukawa, Hirofumi Noda, Hirokazu Odaka, Shoji Ogawa, Anna Ogorzalek, Takashi Okajima, Naomi Ota, Stephane Paltani, Robert Petre, Paul Plucinsky, Frederick S. Porter, Katja Pottschmidt, Kosuke Sato, Toshiki Sato, Makoto Sawada, Hiromi Seta, Megumi Shidatsu, Aurora Simionescu, Randall Smith, Hiromasa Suzuki, Andrew Szymkowiak, Hiromitsu Takahashi, Mai Takeo, Toru Tamagawa, Keisuke Tamura, Takaaki Tanaka, Atsushi Tanimoto, Makoto Tashiro, Yukikatsu Terada, Yuichi Terashima, Yohko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi Tsuru, Hiroyuki Uchida, Nagomi Uchida, Yuusuke Uchida, Hideki Uchiyama, Yoshihiro Ueda, Shinichiro Uno, Jacco Vink, Shin Watanabe, Brian J. Williams, Satoshi Yamada, Shinya Yamada, Hiroya Yamaguchi, Kazutaka Yamaoka, Noriko Yamasaki, Makoto Yamauchi, Shigeo Yamauchi, Tahir Yaqoob, Tomokage Yoneyama, Tessei Yoshida, Mihoko Yukita, Irina Zhuravleva, Ryota Tomaru, Tasuku Hayashi, Tomohiro Hakamata, Daiki Miura, Karri Koljonen, Mike McCollough
    The Astrophysical Journal Letters 977(2) L34-L34 2024年12月11日  査読有り
    Abstract The X-ray binary system Cygnus X-3 (4U 2030+40, V1521 Cyg) is luminous but enigmatic owing to the high intervening absorption. High-resolution X-ray spectroscopy uniquely probes the dynamics of the photoionized gas in the system. In this Letter, we report on an observation of Cyg X-3 with the XRISM/Resolve spectrometer, which provides unprecedented spectral resolution and sensitivity in the 2–10 keV band. We detect multiple kinematic and ionization components in absorption and emission whose superposition leads to complex line profiles, including strong P Cygni profiles on resonance lines. The prominent Fe xxv Heα and Fe xxvi Lyα emission complexes are clearly resolved into their characteristic fine-structure transitions. Self-consistent photoionization modeling allows us to disentangle the absorption and emission components and measure the Doppler velocity of these components as a function of binary orbital phase. We find a significantly higher velocity amplitude for the emission lines than for the absorption lines. The absorption lines generally appear blueshifted by ∼−500–600 km s−1. We show that the wind decomposes naturally into a relatively smooth and large-scale component, perhaps associated with the background wind itself, plus a turbulent, denser structure located close to the compact object in its orbit.
  • Maeda, Y., Yoshida, T., Fukushima, K., Hayashi, K., Kanemaru, Y., Ogawa, S., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yanagi, T., Yoneyama, T., Yoshimoto, M.
    2024年11月  
    XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1226+3347 on 2024-11-10 TT. The source position is determined to be (R.A., Dec.) = (186.488, 33.781), with a systematic error of & sim; 40 arcsec....
  • Marc Audard, Hisamitsu Awaki, Ralf Ballhausen, Aya Bamba, Ehud Behar, Rozenn Boissay-Malaquin, Laura Brenneman, Gregory V Brown, Lia Corrales, Elisa Costantini, Renata Cumbee, Maria Diaz-Trigo, Chris Done, Tadayasu Dotani, Ken Ebisawa, Megan Eckart, Dominique Eckert, Teruaki Enoto, Satoshi Eguchi, Yuichiro Ezoe, Adam Foster, Ryuichi Fujimoto, Yutaka Fujita, Yasushi Fukazawa, Kotaro Fukushima, Akihiro Furuzawa, Luigi Gallo, Javier A García, Liyi Gu, Matteo Guainazzi, Kouichi Hagino, Kenji Hamaguchi, Isamu Hatsukade, Katsuhiro Hayashi, Takayuki Hayashi, Natalie Hell, Edmund Hodges-Kluck, Ann Hornschemeier, Yuto Ichinohe, Manabu Ishida, Kumi Ishikawa, Yoshitaka Ishisaki, Jelle Kaastra, Timothy Kallman, Erin Kara, Satoru Katsuda, Yoshiaki Kanemaru, Richard Kelley, Caroline Kilbourne, Shunji Kitamoto, Shogo Kobayashi, Takayoshi Kohmura, Aya Kubota, Maurice Leutenegger, Michael Loewenstein, Yoshitomo Maeda, Maxim Markevitch, Hironori Matsumoto, Kyoko Matsushita, Dan McCammon, Brian McNamara, François Mernier, Eric D Miller, Jon M Miller, Ikuyuki Mitsuishi, Misaki Mizumoto, Tsunefumi Mizuno, Koji Mori, Koji Mukai, Hiroshi Murakami, Richard Mushotzky, Hiroshi Nakajima, Kazuhiro Nakazawa, Jan-Uwe Ness, Kumiko Nobukawa, Masayoshi Nobukawa, Hirofumi Noda, Hirokazu Odaka, Shoji Ogawa, Anna Ogorzalek, Takashi Okajima, Naomi Ota, Stephane Paltani, Robert Petre, Paul Plucinsky, Frederick Scott Porter, Katja Pottschmidt, Kosuke Sato, Toshiki Sato, Makoto Sawada, Hiromi Seta, Megumi Shidatsu, Aurora Simionescu, Randall Smith, Hiromasa Suzuki, Andrew Szymkowiak, Hiromitsu Takahashi, Mai Takeo, Toru Tamagawa, Keisuke Tamura, Takaaki Tanaka, Atsushi Tanimoto, Makoto Tashiro, Yukikatsu Terada, Yuichi Terashima, Yohko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi G Tsuru, Hiroyuki Uchida, Nagomi Uchida, Yuusuke Uchida, Hideki Uchiyama, Yoshihiro Ueda, Shinichiro Uno, Jacco Vink, Shin Watanabe, Brian J Williams, Satoshi Yamada, Shinya Yamada, Hiroya Yamaguchi, Kazutaka Yamaoka, Noriko Yamasaki, Makoto Yamauchi, Shigeo Yamauchi, Tahir Yaqoob, Tomokage Yoneyama, Tessei Yoshida, Mihoko Yukita, Irina Zhuravleva, Manan Agarwal, Yuken Ohshiro
    Publications of the Astronomical Society of Japan 2024年10月10日  査読有り
    Abstract We present an initial analysis of the X-Ray Imaging and Spectroscopy Mission (XRISM) first-light observation of the supernova remnant (SNR) N 132D in the Large Magellanic Cloud. The Resolve microcalorimeter has obtained the first high-resolution spectrum in the 1.6–10 keV band, which contains K-shell emission lines of Si, S, Ar, Ca, and Fe. We find that the Si and S lines are relatively narrow, with a broadening represented by a Gaussian-like velocity dispersion of $\sigma _v \sim 450$ km s$^{-1}$. However, the Fe He$\alpha$ lines are substantially broadened with $\sigma _v \sim 1670$ km s$^{-1}$. This broadening can be explained by a combination of the thermal Doppler effect due to the high ion temperature and the kinematic Doppler effect due to the SNR expansion. Assuming that the Fe He$\alpha$ emission originates predominantly from the supernova ejecta, we estimate the reverse shock velocity at the time when the bulk of the Fe ejecta were shock heated to be $-1000 \lesssim V_{\rm rs}$ (km s$^{-1}$) $\lesssim 3300$ (in the observer frame). We also find that Fe Ly$\alpha$ emission is redshifted with a bulk velocity of $\sim 890$ km s$^{-1}$, substantially larger than the radial velocity of the local interstellar medium surrounding N 132D. These results demonstrate that high-resolution X-ray spectroscopy is capable of providing constraints on the evolutionary stage, geometry, and velocity distribution of SNRs.
  • Marc Audard, Hisamitsu Awaki, Ralf Ballhausen, Aya Bamba, Ehud Behar, Rozenn Boissay-Malaquin, Laura Brenneman, Gregory V. Brown, Lia Corrales, Elisa Costantini, Renata Cumbee, Maria Diaz Trigo, Chris Done, Tadayasu Dotani, Ken Ebisawa, Megan E. Eckart, Dominique Eckert, Teruaki Enoto, Satoshi Eguchi, Yuichiro Ezoe, Adam Foster, Ryuichi Fujimoto, Yutaka Fujita, Yasushi Fukazawa, Kotaro Fukushima, Akihiro Furuzawa, Luigi Gallo, Javier A. García, Liyi Gu, Matteo Guainazzi, Kouichi Hagino, Kenji Hamaguchi, Isamu Hatsukade, Katsuhiro Hayashi, Takayuki Hayashi, Natalie Hell, Edmund Hodges-Kluck, Ann Hornschemeier, Yuto Ichinohe, Manabu Ishida, Kumi Ishikawa, Yoshitaka Ishisaki, Jelle Kaastra, Timothy Kallman, Erin Kara, Satoru Katsuda, Yoshiaki Kanemaru, Richard Kelley, Caroline Kilbourne, Shunji Kitamoto, Shogo Kobayashi, Takayoshi Kohmura, Aya Kubota, Maurice Leutenegger, Michael Loewenstein, Yoshitomo Maeda, Maxim Markevitch, Hironori Matsumoto, Kyoko Matsushita, Dan McCammon, Brian McNamara, François Mernier, Eric D. Miller, Jon M. Miller, Ikuyuki Mitsuishi, Misaki Mizumoto, Tsunefumi Mizuno, Koji Mori, Koji Mukai, Hiroshi Murakami, Richard Mushotzky, Hiroshi Nakajima, Kazuhiro Nakazawa, Jan-Uwe Ness, Kumiko Nobukawa, Masayoshi Nobukawa, Hirofumi Noda, Hirokazu Odaka, Shoji Ogawa, Anna Ogorzalek, Takashi Okajima, Naomi Ota, Stephane Paltani, Robert Petre, Paul Plucinsky, Frederick S. Porter, Katja Pottschmidt, Kosuke Sato, Toshiki Sato, Makoto Sawada, Hiromi Seta, Megumi Shidatsu, Aurora Simionescu, Randall Smith, Hiromasa Suzuki, Andrew Szymkowiak, Hiromitsu Takahashi, Mai Takeo, Toru Tamagawa, Keisuke Tamura, Takaaki Tanaka, Atsushi Tanimoto, Makoto Tashiro, Yukikatsu Terada, Yuichi Terashima, Yohko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi Tsuru, Hiroyuki Uchida, Nagomi Uchida, Yuusuke Uchida, Hideki Uchiyama, Yoshihiro Ueda, Shinichiro Uno, Jacco Vink, Shin Watanabe, Brian J. Williams, Satoshi Yamada, Shinya Yamada, Hiroya Yamaguchi, Kazutaka Yamaoka, Noriko Yamasaki, Makoto Yamauchi, Shigeo Yamauchi, Tahir Yaqoob, Tomokage Yoneyama, Tessei Yoshida, Mihoko Yukita, Irina Zhuravleva, Xin Xiang, Takeo Minezaki, Margaret Buhariwalla, Dimitra Gerolymatou, Scott Hagen
    The Astrophysical Journal Letters 973(1) L25-L25 2024年9月1日  査読有り
    Abstract We present an analysis of the first two XRISM/Resolve spectra of the well-known Seyfert-1.5 active galactic nucleus (AGN) in NGC 4151, obtained in 2023 December. Our work focuses on the nature of the narrow Fe K α emission line at 6.4 keV, the strongest and most common X-ray line observed in AGN. The total line is found to consist of three components. Even the narrowest component of the line is resolved with evident Fe K α,1 (6.404 keV) and K α,2 (6.391 keV) contributions in a 2:1 flux ratio, fully consistent with neutral gas with negligible bulk velocity. Subject to the limitations of our models, the narrowest and intermediate-width components are consistent with emission from optically thin gas, suggesting that they arise in a disk atmosphere and/or wind. Modeling the three line components in terms of Keplerian broadening, they are readily associated with (1) the inner wall of the “torus,” (2) the innermost optical “broad-line region” (or “X-ray BLR”), and (3) a region with a radius of r ≃ 100 GM/c 2 that may signal a warp in the accretion disk. Viable alternative explanations of the broadest component include a fast-wind component and/or scattering; however, we find evidence of variability in the narrow Fe K α line complex on timescales consistent with small radii. The best-fit models are statistically superior to simple Voigt functions, but when fit with Voigt profiles the time-averaged lines are consistent with a projected velocity broadening of FWHM . Overall, the resolution and sensitivity of XRISM show that the narrow Fe K line in AGN is an effective probe of all key parts of the accretion flow, as it is currently understood. We discuss the implications of these findings for our understanding of AGN accretion, future studies with XRISM, and X-ray-based black hole mass measurements.
  • Yukikatsu Terada, Megumi Shidatsu, Makoto Sawada, Takashi Kominato, So Kato, Ryohei Sato, Minami Sakama, Takumi Shioiri, Yuki Niida, Chikara Natsukari, Makoto S. Tashiro, Kenichi Toda, Hironori Maejima, Katsuhiro Hayashi, Tessei Yoshida, Shoji Ogawa, Yoshiaki Kanemaru, Akio Hoshino, Kotaro Fukushima, Hiromitsu Takahashi, Masayoshi Nobukawa, Tsunefumi Mizuno, Kazuhiro Nakazawa, Shin'ichiro Uno, Ken Ebisawa, Satoshi Eguchi, Satoru Katsuda, Aya Kubota, Naomi Ota, Atsushi Tanimoto, Yuichi Terashima, Yohko Tsuboi, Yuusuke Uchida, Hideki Uchiyama, Shigeo Yamauchi, Tomokage Yoneyama, Satoshi Yamada, Nagomi Uchida, Shin Watanabe, Ryo Iizuka, Rie Sato, Chris Baluta, Matt Holland, Michael Loewenstein, Eric D. Miller, Tahir Yaqoob, Robert S. Hill, Trisha F. Doyle, Efrain Perez-Solis, Morgan D. Waddy, Mark Mekosh, Joseph B. Fox, Toshihiro Takagi, Yugo Motogami, Katja Pottschmidt, Teruaki Enoto, Takaaki Tanaka
    Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 61-61 2024年8月21日  
  • Katsuhiro Hayashi, Makoto S. Tashiro, Yukikatsu Terada, Tessei Yoshida, Shoji Ogawa, Yoshiaki Kanemaru, Kotaro Fukushima, Akio Hoshino, Hiromitsu Takahashi, Masayoshi Nobukawa, Tsunefumi Mizuno, Kazuhiro Nakazawa, Shin'ichiro Uno, Ken Ebisawa, Satoshi Eguchi, Satoru Katsuda, Takao Kitaguchi, Aya Kubota, Naomi Ota, Megumi Shidatsu, Atsushi Tanimoto, Yuichi Terashima, Yohko Tsuboi, Yuusuke Uchida, Hideki Uchiyama, Shigeo Yamauchi, Tomokage Yoneyama, Satoshi Yamada, Nagomi Uchida, Seiko Sakurai, Shin Watanabe, Ryo Iizuka, Rie Sato, Chris Baluta, Takayuki Tamura, Yasushi Fukazawa, Hirokazu Odaka, Tsubasa Tamba, Ryohei Sato, Sou Kato, Minami Sakama, Takumi Shioiri, Yuki Niida, Natsuki Sakamoto, Noboru Nemoto, Yuki Omiya, Nari Suzuki, Toshihiro Takagi, Yugo Motogami, Matt Holland, Michael Loewenstein, Eric D. Miller, Tahir Yaqoob, Robert S. Hill, Trisha F. Doyle, Efrain Perez-Solis, Morgan D. Waddy, Mark Mekosh, Joseph B. Fox, Matteo Guainazzi, Jan-Uwe Ness, Hironori Maejima, Kenichi Toda, Chikara Natsukari
    Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 60-60 2024年8月21日  
  • Megumi Shidatsu, Yukikatsu Terada, Takashi Kominato, So Kato, Ryohei Sato, Minami Sakama, Takumi Shioiri, Yugo Motogami, Yuki Niida, Toshihiro Takagi, Chikara Natsukari, Makoto S. Tashiro, Kenichi Toda, Hironori Maejima, Shin Watanabe, Ryo Iizuka, Rie Sato, Chris Baluta, Katsuhiro Hayashi, Tessei Yoshida, Shoji Ogawa, Yoshiaki Kanemaru, Kotaro Fukushima, Akio Hoshino, Hiromitsu Takahashi, Masayoshi Nobukawa, Tsunefumi Mizuno, Kazuhiro Nakazawa, Shin'ichiro Uno, Ken Ebisawa, Satoshi Eguchi, Satoru Katsuda, Aya Kubota, Naomi Ota, Atsushi Tanimoto, Yuichi Terashima, Yohko Tsuboi, Yuusuke Uchida, Hideki Uchiyama, Shigeo Yamauchi, Tomokage Yoneyama, Satoshi Yamada, Nagomi Uchida, Matt Holland, Michael Loewenstein, Eric D. Miller, Tahir Yaqoob, Robert S. Hill, Trisha F. Doyle, Efrain Perez-Solis, Morgan D. Waddy, Mark Mekosh, Joseph B. Fox
    Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 235-235 2024年8月21日  
  • Yohko Tsuboi, Koichiro Akasu, Noboru Nemoto, Tomokage Yoneyama, Marina Yoshimoto, Kotaro Fukushima, Katsuhiro Hayashi, Yoshiaki Kanemaru, Shoji Ogawa, Tessei Yoshida, Marc Audard, Ehud Behar, Shun Inoue, Yuiko Ishihara, Takayoshi Komura, Yoshitomo Maeda, Misaki Mizumoto, Masayoshi Nobukawa, Katja Pottschmidt, Megumi Shidatsu, Yukikatsu Terada, Yuichi Terashima, Hiroyuki Uchida
    Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 236-236 2024年8月21日  
  • Yoshiaki Kanemaru, Ryo Iizuka, Yoshitomo Maeda, Takashi Okajima, Takayuki Hayashi, Kazuhiro Kiyokane, Yuto Nihei, Takashi Kominato, Manabu Ishida, Chikara Natsukari, Shin Watanabe, Kosuke Sato, Yukikatsu Terada, Katsuhiro Hayashi, Chris Baluta, Tessei Yoshida, Akio Hoshino, Shoji Ogawa, Kotaro Fukushima, Hiromitsu Takahashi, Masayoshi Nobukawa, Tsunefumi Mizuno, Kazuhiro Nakazawa, Shin'ichiro Uno, Ken Ebisawa, Satoshi Eguchi, Satoru Katsuda, Aya Kubota, Naomi Ota, Megumi Shidatsu, Atsushi Tanimoto, Yuichi Terashima, Yohko Tsuboi, Yuusuke Uchida, Hideki Uchiyama, Shigeo Yamauchi, Yoneyama Tomokage, Satoshi Yamada, Nagomi Uchida, Rie Sato, Matt Holland, Michael Loewenstein, Eric D. Miller, Tahir Yaqoob, Robert S. Hill, Trisha F. Doyle, Efrain Perez-Solis, Morgan D. Waddy, Mark Mekosh, Joseph B. Fox, Makoto S. Tashiro, Kenichi Toda, Hironori Maejima
    Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 224-224 2024年8月21日  
  • Makoto S. Tashiro, Shin Watanabe, Hironori Maejima, Kenichi Toda, Kyoko Matsushita, Hiroya Yamaguchi, Richard L. Kelley, Lillian S. Reichenthal, Leslie S. Hartz, Robert Petre, Brian J. Williams, Matteo Guainazzi, Andrea Santovincenzo, Elisa Costantini, Yoh Takei, Yoshitaka Ishisaki, Ryuichi Fujimoto, Joy Henegar-Leon, Gary Sneiderman, Hiroshi Tomida, Koji Mori, Hiroshi Nakajima, Yukikatsu Terada, Matt Holland, Micheal Loewenstein, Tomothey Kallman, Jelle Kaastra, Eric Miller, Makoto Sawada, Chris Done, Teruaki Enoto, Aya Bamba, Paul Plucinsky, Yoshitaka Ueda, Erin Kara, Irina Zhuravleva, Yutaka Fujita, Jose Antonio Quero, Yoshitaka Arai, Marc Audard, Hisamitsu Awaki, Chris Baluta, Nobutaka Bando, Ehud Behar, Thomas Bialas, Rozenn Boissay-Malaquin, Laura Brenneman, Gregory V. Brown, Meng Chiao, Lia Corrales, Renata Cumbee, Cor de Vries, Jan-Willem den Herder, Maria Diaz-Trigo, Michael DiPirro, Tadayasu Dotani, Jacobo Ebrero Carrero, Ken Ebisawa, Megan Eckart, Dominique Eckart, Satoshi Eguchi, Yuichiro Ezoe, Carlo Ferrgno, Adam Foster, Yasushi Fukazawa, Kotaro Fukushima, Akihiro Furuzawa, Luigi Gallo, Nathalie Gorter, Martin Grim, Liyi Gu, Koichi Hagino, Kenji Hamaguchi, Isamu Hatsukade, Katsuhiro Hayashi, Takayuki Hayashi, Natalie Hell, Edmund Hodges-Kluck, Takafumi Horiuchi, Ann Hornschemeier, Akio Hoshino, Yuto Ichinohe, Chisato Ikuta, Ryo Iizuka, Daiki Ishi, Manabu Ishida, Naoki Ishihama, Kumi Ishikawa, Kosei Ishimura, Tess Jaffe, Satoru Katsuda, Yoshiaki Kanemaru, Steven Kenyon, Caroline Kilbourne, Mark Kimball, Shunji Kitamoto, Shogo Kobayashi, Akihide Kobayashi, Takayoshi Kohmura, Aya Kubota, Maurice Leutenegger, Muzi Li, Yoshitomo Maeda, Maxim Markevitch, Hironori Matsumoto, Keiichi Matsuzaki, Dan McCammon, Brian McLaughlin, Brian McNamara, Josegh Miko, Jon Miller, Kenji Minesugi, Shinji Mitani, Ikuyuki Mitsuishi, Misaki Mizumoto, Tsunefumi Mizuno, Koji Mukai, Hiroshi Murakami, Richard Mushotzky, Kazuhiro Nakazawa, Chikara Natsukari, Jan-Uwe Ness, Kenichiro Nigo, Mari Nishiyama, Kumiko Nobukawa, Masayoshi Nobukawa, Hirofumi Noda, Hirokazu Odaka, Mina Ogawa, Shoji Ogawa, Takashi Okajima, Atsushi Okamoto, Naomi Ota, Masanobu Ozaki, Stephane Paltani, F. Scott Porter, Katja Pottschmidt, Takahiro Sasaki, Kosuke Sato, Rie Sato, Toshiki Sato, Yoichi Sato, Hiromi Seta, Maki Shida, Megumi Shidatsu, Shuhei Shigeto, Russel Shipman, Keisuke Shinozaki, Peter Shirron, Aurora Simionescu, Randall Smith, Young Soong, Hiromasa Suzuki, Andy Szymkowiak, Hiromitsu Takahashi, Mai Takeo, Toru Tamagawa, Keisuke Tamura, Takaaki Tanaka, Atsushi Tanimoto, Yoichi Terashima, Yohko Tsuboi, Masahiro Tsujimoto, Hiroshi Tsunemi, Takeshi Tsuru, Hiroyuki Uchida, Nagomi Ucghida, Yuusuke Uchida, Hideki Uchiyama, Shinichiro Uno, Erik Van der Meer, Jacco Vink, Michael Wittheof, Rob Wolf, Satoshi Yamada, Shinya Yamada, Kazutaka Yamaoka, Noriko Yamasaki, Makoto Yamauchi, Shigeo Yamauchi, Keiichi Yamagase, Tahir Yaqoob, Susumu Yasuda, Tomokage Yoneyama, Tessei Yoshida
    Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 52-52 2024年8月21日  
  • Ogawa, S., Fukushima, K., Hayashi, K., Kanemaru, Y., Yoshida, T., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yanagi, T., Yoneyama, T., Yoshimoto, M.
    2024年8月  
    XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1137-6516 on 2024-08-13 TT. The source position is determined to be (R.A., Dec.) = (174.244, -65.273), with a systematic error of & ndash; 40 arcsec....
  • Ogawa, S., Fukushima, K., Hayashi, K., Kanemaru, Y., Yoshida, T., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yanagi, T., Yoneyama, T., Yoshimoto, M.
    2024年8月  
    XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1142-6522 on 2024-08-13 TT. The source position is determined to be (R.A., Dec.) = (175.418, -65.363), with a systematic error of & ndash; 40 arcsec....
  • Ogawa, S., Fukushima, K., Hayashi, K., Kanemaru, Y., Yoshida, T., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yanagi, T., Yoneyama, T., Yoshimoto, M.
    2024年8月  
    XRISM/Xtend Transient Search (XTS) detected an X-ray flare from the X-ray source XRISM J1142-6522, whose possible counterpart is 2MASS J11414215-6521298 at 101 pc, on 2024-08-14 TT. This is the second report by XRISM of a brightening of this source following the last one (ATel #16774)....
  • Ogawa, S., Fukushima, K., Hayashi, K., Kanemaru, Y., Yoshida, T., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yanagi, T., Yoneyama, T., Yoshimoto, M.
    2024年8月  
    XRISM/Xtend Transient Search (XTS) detected X-ray flares from the X-ray source XRISM J1142-6522, whose possible counterpart is 2MASS J11414215-6521298 at 101 pc, on 2024-08-15 TT. We report the largest flare in this period although the activity is continued....
  • Ogawa, S., Fukushima, K., Hayashi, K., Kanemaru, Y., Yoshida, T., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yanagi, T., Yoneyama, T., Yoshimoto, M.
    2024年8月  
    XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1140-6519 on 2024-08-17 TT. The source position is determined to be (R.A., Dec.) = (175.081, -65.316), with a systematic error of & sim; 40 arcsec....
  • Fukushima, K., Hayashi, K., Kanemaru, Y., Ogawa, S., Yoshida, T., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yanagi, T., Yoneyama, T., Yoshimoto, M.
    2024年8月  
    XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1745-2914 on 2024-08-29 TT. The source position is determined to be (R.A., Dec.) = (266.276, -29.246), with a systematic error of & sim; 40 arcsec....
  • Fukushima, K., Hayashi, K., Kanemaru, Y., Ogawa, S., Yoshida, T., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yoneyama, T., Yoshimoto, M.
    2024年7月  
    XRISM/Xtend Transient Search (XTS) detected an X-ray flare from the X-ray source XRISM J1558+2534, whose plausible counterpart is MS Ser, on 2024-07-02 TT. This is the second flare of this source during the XRISM observation of T CrB (ATel #16683)....
  • Fukushima, K., Hayashi, K., Kanemaru, Y., Ogawa, S., Yoshida, T., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yoneyama, T., Yoshimoto, M.
    2024年7月  
    XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1558+2534 on 2024-07-01 TT. The source position is determined to be (R.A., Dec.) = (239.679 deg, +25.573 deg), with systematic error of & sim; 40 arcsec....
  • Yoshida, T., Fukushima, K., Hayashi, K., Kanemaru, Y., Ogawa, S., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yoneyama, T., Yoshimoto, M.
    2024年7月  
    XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1138-3742 on 2024-07-19 TT. The source position is determined to be (R.A., Dec.) = (174.415 deg, -37.707 deg), with a systematic error of -40 arcsec....
  • Hayashi, K., Fukushima, K., Kanemaru, Y., Ogawa, S., Yoshida, T., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yoneyama, T., Yoshimoto, M.
    2024年7月  
    XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1138-3742, whose plausible counterpart is UCAC2 15735923, on 2024-07-21....
  • Yoshida, T., Fukushima, K., Hayashi, K., Kanemaru, Y., Ogawa, S., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yoneyama, T., Yoshimoto, M.
    2024年6月  
    XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source candidate XRISM J1045-5954 on 2024-06-10 TT in the direction of the Carina Nebula....
  • K. Fukushima, S. B. Kobayashi, K. Matsushita
    Astronomy & Astrophysics 686 2024年6月  査読有り筆頭著者責任著者
  • Yoshida, T., Fukushima, K., Hayashi, K., Kanemaru, Y., Ogawa, S., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yoneyama, T., Yoshimoto, M.
    2024年5月  
    XRISM/Xtend Transient Search (XTS) detected an X-ray outburst from a high-mass X-ray binary AX J1910.7+0917 on 2024-04-28 TT. Due to a bad time interval of XRISM, the outburst start time was not detected, but only a rough constraint, 2024-04-28 19:52 & ndash; 20:41 TT, is given....
  • Yoshida, T., Fukushima, K., Hayashi, K., Kanemaru, Y., Ogawa, S., Audard, M., Behar, E., Inoue, S., Ishihara, Y., Kohmura, T., Maeda, Y., Mizumoto, M., Nobukawa, M., Pottschmidt, K., Shidatsu, M., Terada, Y., Terashima, Y., Tsuboi, Y., Uchida, H., Yoneyama, T., Yoshimoto, M., Fukazawa, Y., Plucinsky, P., bamba, A., Murakami, H., Tsuru, T., Ezoe, Y., Nakajima, H., Enoto, T., Nobukawa, K., Vink, J., Hamaguchi, K., Odaka, H., Sato, T., Suzuki, H., Ichinohe, Y., Sawada, M., Foster, A., Ishida, M., Smith, R., Katsuda, S., Tamura, K., Matsumoto, H., Tanaka, T., Mori, K.
    2024年5月  
    XRISM team detected SN2024iss with Xtend during the ToO observation from 2024-05-24 16:56 TT to 2024-05-25 16:54 TT aimed at (RA, DEC) = (12h 59m 06s, 28d 48m 36s)....
  • Hayato Sugiyama, Masaki Ueda, Kotaro Fukushima, Shogo B. Kobayashi, Noriko Y. Yamasaki, Kosuke Sato, Kyoko Matsushita
    Publications of the Astronomical Society of Japan 75(6) 1324-1336 2023年12月1日  査読有り
    Observations of the hot X-ray emitting interstellar medium in the Milky Way are important for studying the stellar feedback and for understanding the formation and evolution of galaxies. We present measurements of the soft X-ray background emission for 130 Suzaku observations at 75° < l < 285° and |b| > 15°. With the standard soft X-ray background model consisting of the local hot bubble and of the Milky Way halo, residual structures remain at 0.7-1 keV in the spectra of some regions. Adding a collisional-ionization-equilibrium component with a temperature of ∼0.8 keV, much higher than the virial temperature of the Milky Way, significantly reduces the derived C-statistic for 56 out of 130 observations. The emission measure of the 0.8 keV component varies by more than an order of magnitude: assuming the solar abundance, the median value is and the 16th-84th percentile range is. Regions toward the Orion-Eridanus superbubble, having a large cavity extending from the Ori OB1 association, have the highest emission measures of the 0.8 keV component. While the scatter is large, the emission measures tend to be higher toward lower galactic latitudes. We discuss possible biases caused by the solar wind charge exchange, stars, and background groups. The 0.8 keV component is probably heated by supernovae in the Milky Way disk, possibly related to Galactic fountains.
  • Kotaro Fukushima, Shogo B. Kobayashi, Kyoko Matsushita
    Astrophysical Journal 953(1) 2023年8月1日  査読有り筆頭著者責任著者
    Chemical elements in the hot medium permeating early-type galaxies, groups, and clusters make such objects an excellent laboratory for studying metal enrichment and cycling processes on the largest scales of the universe. Here, we report the analysis by the XMM-Newton Reflection Grating Spectrometer of 14 early-type galaxies, including the well-known brightest cluster galaxies of Perseus, for instance. The spatial distribution of the O/Fe, Ne/Fe, and Mg/Fe ratios is generally flat in the central 60″ regions of each object, irrespective of whether or not a central Fe abundance drop has been reported. Common profiles between noble gas and normal metal suggest that the dust depletion process does not work predominantly in these systems. Therefore, observed abundance drops are possibly attributed to other origins, such as systematics in the atomic codes. Giant systems with a high ratio of gas mass to luminosity tend to hold a hot gas (∼2 keV) yielding the solar N/Fe, O/Fe, Ne/Fe, Mg/Fe, and Ni/Fe ratios. Contrarily, light systems in a sub-keV temperature regime, including isolated or group-centered galaxies, generally exhibit supersolar N/Fe, Ni/Fe, Ne/O, and Mg/O ratios. We find that the latest supernova nucleosynthesis models fail to reproduce such a supersolar abundance pattern. Possible systematic uncertainties contributing to these high abundance ratios of cool objects are also discussed in tandem with the crucial role of future X-ray missions.
  • Masaki Ueda, Hayato Sugiyama, Shogo B. Kobayashi, Kotaro Fukushima, Noriko Y. Yamasaki, Kosuke Sato, Kyoko Matsushita
    Publications of the Astronomical Society of Japan 74(6) 1396-1414 2022年12月1日  査読有り
    We present measurements of the soft X-ray background emission for 130 Suzaku observations at 75◦ < l < 285◦ and |b| > 15◦ obtained from 2005 to 2015, covering nearly one solar cycle. In addition to the standard soft X-ray background model consisting of the local hot bubble and the Milky Way Halo (MWH), we include a hot collisional-ionization-equilibrium component with a temperature of ∼0.8 keV to reproduce spectra of a significant fraction of the lines of sight. Then, the scatter in the relation between the emission measure vs. temperature of the MWH component is reduced. Here, we exclude time ranges with high count rates to minimize the effect of the solar wind charge exchange (SWCX). However, the spectra of almost the same lines of sight are inconsistent. The heliospheric SWCX emissions likely contaminate and give a bias in measurements of temperature and the emission measure of the MWH. Excluding the data around the solar maximum and using the data taken before the end of 2009, at |b| > 35◦ and 105◦ < l < 255◦, the temperature (0.22 keV) and emission measure (2 × 10−3 cm−6 pc) of the MWH are fairly uniform. The increase of the emission measure toward the lower Galactic latitude at |b| < 35◦ indicates the presence of a disk-like morphology component. A composite model which consists of disk-like and spherical-morphology components also reproduces the observed emission measure distribution of MWH. In this case, the hydrostatic mass at a few tens of kiloparsec from the Galactic center agrees with the gravitational mass of the Milky Way. The plasma with the virial temperature likely fills the Milky Way halo in nearly hydrostatic equilibrium. Assuming a gas metallicity of 0.3 solar, the upper limit of the gas mass of the spherical component out to 250 kpc, or the virial radius, is ∼ a few × 1010 M☉
  • Kotaro Fukushima, Shogo B. Kobayashi, Kyoko Matsushita
    Monthly Notices of the Royal Astronomical Society 514(3) 4222-4238 2022年8月1日  査読有り筆頭著者責任著者
    Here, we present results from over 500 ksChandra and XMM-Newton observations of the cool core of the Centaurus cluster. We investigate the spatial distributions of the O, Mg, Si, S, Ar, Ca, Cr, Mn, Fe, and Ni abundances in the intracluster medium with CCD detectors, and those of N, O, Ne, Mg, Fe, and Ni with the Reflection Grating Spectrometer (RGS). The abundances of most of the elements show a sharp drop within the central 18 arcsec, although different detectors and atomic codes give significantly different values. The abundance ratios of the above elements, including Ne/Fe with RGS, show relatively flat radial distributions. In the innermost regions with the dominant Fe-L lines, the measurements of the absolute abundances are challenging. For example, AtomDB and SPEXACT give Fe = 0.5 and 1.4 solar, respectively, for the spectra from the innermost region. These results suggest some systematic uncertainties in the atomic data and response matrices at least partly cause the abundance drop rather than the metal depletion into the cold dust. Except for super-solar N/Fe and Ni/Fe, sub-solar Ne/Fe, and Mg/Fe, the abundance pattern agrees with the solar composition. The entire pattern is challenging to reproduce with the latest supernova nucleosynthesis models. Observed super-solar N/O and comparable Mg abundance to stellar metallicity profiles imply that the mass-loss winds dominate the intracluster medium in the brightest cluster galaxy. The solar Cr/Fe and Mn/Fe ratios indicate a significant contribution of near-and sub-Chandrasekhar mass explosions of Type Ia supernovae.
  • Kotaro Fukushima, Hiroya Yamaguchi, Patrick O. Slane, Sangwook Park, Satoru Katsuda, Hidetoshi Sano, Laura A. Lopez, Paul P. Plucinsky, Shogo B. Kobayashi, Kyoko Matsushita
    Astrophysical Journal 897(1) 2020年7月1日  査読有り筆頭著者責任著者
    Despite their importance, a detailed understanding of Type Ia supernovae (SNe Ia) remains elusive. X-ray measurements of the element distributions in supernova remnants (SNRs) offer important clues for understanding the explosion and nucleosynthesis mechanisms for SNe Ia. However, it is challenging to observe the entire ejecta mass in X-rays for young SNRs, because the central ejecta may not have been heated by the reverse shock yet. Here we present over 200 kilosecond Chandra observations of the Type Ia SNR G344.7-0.1, whose age is old enough for the reverse shock to have reached the SNR center, providing an opportunity to investigate the distribution of the entire ejecta mass. We reveal a clear stratification of heavy elements with a centrally peaked distribution of the Fe ejecta surrounded by intermediate-mass elements (IMEs: Si, S, Ar Ca) with an arc-like structure. The centroid energy of the Fe K emission is marginally lower in the central Fe-rich region than in the outer IME-rich regions, suggesting that the Fe ejecta were shock-heated more recently. These results are consistent with the prediction for standard SN Ia models, where the heavier elements are synthesized in the interior of an exploding white dwarf. We find, however, that the peak location of the Fe K emission is slightly offset to the west with respect to the geometric center of the SNR. This apparent asymmetry is likely due to the inhomogeneous density distribution of the ambient medium, consistent with our radio observations of the ambient molecular and neutral gas.

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