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  2. 土居 明広

土居 明広

ドイ アキヒロ  (Akihiro DOI)

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 助教
総合研究大学院大学 物理科学研究科 宇宙科学専攻 助教
学位
博士 (理学)(2005年3月 東京大学)
研究者番号
90403641
ORCID ID
 https://orcid.org/0000-0003-4384-9568
J-GLOBAL ID
201101033666007265
researchmap会員ID
B000004312

研究キーワード

 11

研究分野

 3

経歴

 3

論文

 113
  • Kazunori Akiyama, Kotaro Niinuma, Kazuhiro Hada, Akihiro Doi, Yoshiaki Hagiwara, Aya Higuchi, Mareki Honma, Tomohisa Kawashima, Dimitar Kolev, Shoko Koyama, Sho Masui, Ken Ohsuga, Hidetoshi Sano, Hideki Takami, Yuh Tsunetoe, Yoshinori Uzawa, Takuya Akahori, Yuto Akiyama, Peter Galison, Takayuki J. Hayashi, Tomoya Hirota, Makoto Inoue, Yuhei Iwata, Michael Johnson, Motoki Kino, Yutaro Kofuji, Yosuke Mizuno, Kotaro Moriyama, Hiroshi Nagai, Kenta Nakamura, Shota Notsu, Fumie Ono, Yoko Oya, Tomoaki Oyama, Hannah Rana, Hiromi Saida, Ryo Saito, Yoshihiko Saito, Mahito Sasada, Satoko Sawada-Satoh, Mikiya M. Takahashi, Mieko Takamura, Edward Tong, Hiroyuki Tsuji, Shogo Yoshioka, Yoshimasa Watanabe
    Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 91-91 2024年8月23日  
  • Kohji Tsumura, Hideo Matsuhara, Koji S. Kawabata, Hiroshi Akitaya, Shuji Matsuura, Haruki Fukui, Akihiro Miyasaka, Keisuke Shinozaki, Akihiro Doi, Daisuke Yonetoku
    Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 86-86 2024年8月23日  
  • Koji S. Kawabata, Kohji Tsumura, Daisuke Yonetoku, Hideo Matsuhara, Shuji Matsuura, Akihiro Doi, Hiroshi Akitaya, Tomoya Hori
    Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 203-203 2024年8月23日  
  • Daisuke Yonetoku, Akihiro Doi, Tatehiro Mihara, Hideo Matsuhara, Takanori Sakamoto, Kohji Tsumura, Kunihito Ioka, Makoto Arimoto, Teruaki Enoto, Kenjiro Fujimoto, Hatsune Goto, Shuichi Gunji, Junko S. Hiraga, Shintaro Ikunaga, Nobuyuki Kawai, Ryuji Kondo, Shunsuke Kurosawa, Junyi Li, Yoshitomo Maeda, Ikuyuki Mitsuishi, Toshio Murakami, Issin Nagataka, Yujin Nakagawa, Naoki Ogino, Taiki Owari, Ryuji Sato, Masataka Sato, Tomoya Sato, Tatsuya Sawano, Motoko Serino, Hsien-Chieh Shen, Satoshi Sugita, Shuta Takahashi, Toru Tamagawa, Keisuke Tamura, Takaaki Tanaka, Toru Tanimori, Makoto S. Tashiro, Takumi Togashi, Hiroshi Tomida, Keito Watanabe, Kazutaka Yamaoka, Makoto Yamauchi, Yoichi Yatsu, Atsumasa Yoshida, Hiroshi Akitaya, Akihiko Fukui, Haruki Fukui, Yoshifusa Ita, Koji Kawabata, Shuji Matsuura, Akihiro Miyasaka, Kentaro Motohara, Norio Narita, Hirofumi Noda, Hirofumi Okita, Kei Sano, Keisuke Shinozaki, Sou Tajima, Yuji Urata, Takehiko Wada, Kenshi Yanagisawa, Michitoshi Yoshida, Nobutaka Bando, Ichiro Jikuya, Kenji Minesugi, Yasuyuki Miyazaki, Yusuke Kono, Naoki Takase, Shunichi Nakatsubo, Tooru Kaga, Katsuaki Asano, Kohei Inayoshi, Susumu Inoue, Hirotaka Ito, Hideyuki Izumiura, Norita Kawanaka, Tomoya Kinugawa, Shota Kisaka, Kenta Kiuchi, Kotaro Kyutoku, Jin Matsumoto, Akira Mizuta, Kohta Murase, Hiroki Nagakura, Shigehiro Nagataki, Yoshikazu Nakada, Takashi Nakamura, Yuu Niino, Yudai Suwa, Keitaro Takahashi, Takahiro Tanaka, Kenji Toma, Tomonori Totani, Ryo Yamazaki, Jun'ichi Yokoyama, Yuichi Harikane, Masaomi Tanaka, Shigeo Kimura, Mariko Kimura
    Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 75-75 2024年8月21日  
  • Takayuki J Hayashi, Akihiro Doi, Hiroshi Nagai
    Monthly Notices of the Royal Astronomical Society 530(3) 2590-2607 2024年4月15日  
    ABSTRACT A substantial fraction of quasars display broad absorption lines (BALs) in their rest-frame ultraviolet spectra. While the origin of BALs is thought to be related to the accretion disc wind, it remains unclear whether the observed ratio of BAL to non-BAL quasars is a result of orientation. We conducted observations of 48 BAL quasars and the same number of non-BAL quasars at 322 MHz using the Giant Metrewave Radio Telescope. Combined with previous flux measurements ranging from MHz to GHz frequencies, we compared continuum radio spectra between the two quasar groups. These data offer insights into low-frequency radio properties that have been difficult to investigate with previous observations only at GHz frequencies. Our results show that 73 ± 13 per cent of the BAL quasars exhibit steep or peaked spectra, a higher proportion than the 44 ± 14 per cent observed in the non-BAL quasars. In contrast, there are no discernible differences between the two quasar groups in the radio luminosity, peak frequency, and spectral index distributions of sources with steep or peaked spectra and sources with flat or inverted spectra. Generally, as the jet axis and line of sight become closer to parallel, quasars exhibit flat or inverted spectra rather than steep or peaked spectra. Therefore, these results suggest that BAL quasars are more frequently observed farther from the jet axis than non-BAL quasars. However, given that a certain proportion of BAL quasars exhibit flat or inverted spectra, more than the simple orientation scenario is required to elucidate the radio properties of BAL quasars.
もっとみる

MISC

 66
  • 坪井昌人, 斉藤宏文, 村田泰宏, 川原康介, 吉原圭介, 亀谷和久, 紀伊恒男, 土居明広, 望月奈々子, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 太刀川純孝, 小林秀行, 川口則行, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 紀基樹, 平林久, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 亀野誠二, 西尾正則, 但木兼一, 佐藤麻美子, 藤沢健太, 輪島清昭, 楠野こず枝, 浅田圭一, 井上允
    日本天文学会年会講演予稿集 2009 254 2009年8月20日  
  • 村田泰宏, 齋藤宏文, 坪井昌人, 土居明広, 望月奈々子, 亀谷和久, 紀伊恒男, 川原康介, 吉原圭介, 竹内央, 朝木義晴, 樋口健, 岸本直子, 坂井真一郎, 小松敬治, 太刀川純孝, 平林久, 小林秀行, 武士俣健, 鈴木駿作, 梅本智文, 萩原喜昭, 河野祐介, 氏原秀樹, 紀基樹, 永井洋, 川口則行, 浅田圭一, 井上允, 小川英夫, 木村公洋, 春日隆, 亀野誠二, 今井裕, 面高俊宏, 佐藤麻美子, 但木謙一, 藤沢健太, 輪島清昭, 須藤広志
    日本天文学会年会講演予稿集 2009 254 2009年8月20日  
  • 黒岩 宏一, 木村 公洋, 小川 英夫, 千葉 正克, 氏原 秀樹, 春日 隆, 土居 明広, 村田 泰宏, 坪井 昌人, 三谷 友彦
    電子情報通信学会技術研究報告. A・P, アンテナ・伝播 109(1) 1-5 2009年4月2日  
    我々は、電波天文衛星(ASTRO-G)搭載望遠鏡と、地上の電波望遠鏡との間でVLBI観測を行い、地球上だけでは不可能である超高分解能電波観測を行うことを計画している。ここでは衛星搭載電波望遠鏡光学系および搭載8GHz帯受信機の開発状況について報告する。この望遠鏡は口径約9メートルの主鏡で構成されるオフセットカセグレンアンテナであり、カセグレン焦点付近に、43,22,8GHz帯のフィードホーンを並置する。フィードホーンとしてマルチモードホーンを採用し、効率のよいカセグレン光学系を設計した。
  • 坪井昌人, 斉藤宏文, 太刀川純孝, 村田泰宏, 紀伊恒男, 土居明広, 望月奈々子, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 浅田圭一, 川原康介, 吉原圭介, 亀谷和久, 井上允, 小林秀行, 川口則行, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 紀基樹, 平林久, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 亀野誠二, 西尾正則, 但木兼一, 佐藤麻美子, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集 2009 249 2009年2月20日  
  • 村田泰宏, 齋藤宏文, 坪井昌人, 土居明広, 望月奈々子, 浅田圭一, 亀谷和久, 紀伊恒男, 川原康介, 吉原圭介, 吉川真, 竹内央, 朝木義晴, 樋口健, 岸本直子, 坂井真一郎, 小松敬治, 太刀川純孝, 平林久, 井上允, 武士俣健, 鈴木駿作, 梅本智文, 萩原喜昭, 河野祐介, 氏原秀樹, 紀基樹, 永井洋, 小林秀行, 川口則行, 小川英夫, 木村公洋, 春日隆, 亀野誠二, 今井裕, 面高俊宏, 佐藤麻美子, 但木謙一, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集 2009 247 2009年2月20日  
  • 坪井昌人, 齋藤宏文, 太刀川純孝, 村田泰宏, 紀伊恒男, 土居明広, 望月奈々子, 紀基樹, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 浅田圭一, 川原康介, 吉原圭介, 井上允, 小林秀行, 川口則行, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 平林久, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 亀野誠二, 西尾正則, 佐藤麻美子, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集 2008 258 2008年8月20日  
  • 村田泰宏, 齋藤宏文, 坪井昌人, 土居明広, 望月奈々子, 紀基樹, 紀伊恒男, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 太刀川純孝, 浅田圭一, 川原康介, 平林久, 井上允, 小林秀行, 川口則幸, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 武士俣健, 亀野誠二, 面高俊宏, 西尾正則, 今井裕, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集 2008 258 2008年8月20日  
  • Sugiyama Koichiro, Fujisawa Kenta, Doi Akihiro, HONMA Mareki, KOBAYASHI Hideyuki, BUSHIMATA Takeshi, MOCHIZUKI Nanako, MURATA Yasuhiro
    PASJ : publications of the Astronomical Society of Japan 60(1) 23-35 2008年2月25日  
  • 村田泰宏, 斉藤宏文, 坪井昌人, 太刀川純孝, 土居明広, 望月奈々子, 紀基樹, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 浅田圭一, 川原康介, 平林久, 井上允, 小林秀行, 川口則幸, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 亀野誠二, 面高俊宏, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集 2008 264 2008年2月20日  
  • 坪井昌人, 斉藤宏文, 太刀川純孝, 村田泰宏, 土居明広, 望月奈々子, 紀基樹, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 浅田圭一, 川原康介, 井上允, 小林秀行, 川口則幸, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 平林久, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 亀野誠二, 西尾正則, 佐藤麻美子, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集 2008 262 2008年2月20日  
  • 坪井昌人, 斉藤宏文, 太刀川純孝, 村田泰宏, 土居明広, 望月奈々子, 紀基樹, 吉川真, 朝木義晴, 竹内央, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 浅田圭一, 川原康介, 井上允, 小林秀行, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 平林久, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 亀野誠二, 西尾正則, 佐藤麻美子, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集 2007 281 2007年8月20日  
  • 竹内央, 吉川真, 加藤隆二, 朝木義晴, 齋藤宏文, 坪井昌人, 村田泰宏, 土居明広, 川原康介, 中村信一, 中村涼, 工藤信夫, 石島義之, 近藤義典, 山元透, 國森裕生, 久保岡俊宏, 後藤忠広, 大坪俊通
    日本天文学会年会講演予稿集 2007 281 2007年8月20日  
  • Koichiro Sugiyama, Kenta Fujisawa, Mareki Honma, Akihiro Doi, Nanako Mochizuki, Yasuhiro Murata, Yasuko Isono
    Proceedings of the International Astronomical Union 3(242) 176-177 2007年3月  査読有り
    We are using a Japanese VLBI network (JVN) for VLBI observations of 6.7-GHz methanol masers associated with massive star-forming regions. Here we present results for Cepheus A (Cep A) from observations taken on September 9, 2006. The distribution of the maser spots indicates either a spherical bubble or a disk having an inclination of several tens degree. We construct a disk model with an inclination of ~70° and a radius of ~700 AU. From a luminosity of 1.7 × 104 L for a source observed in this region, the excitation of the maser is probably radiative. © 2008 International Astronomical Union.
  • Akihiro Doi, Kenta Fujisawa, Mareki Honma, Koichiro Sugiyama, Yasuhiro Murata, Nanako Mochizuki, Yasuko Isono
    Proceedings of the International Astronomical Union 3(242) 148-149 2007年3月  査読有り筆頭著者
    The Japanese VLBI network (JVN) has begun observations of 6.7-GHz methanol masers associated with massive star-forming regions. The JVN is a newly-established VLBI array with baselines ranging from 50 to 2560 km spread across the Japanese islands. Three observing bands of 6.7, 8.4, and 22 GHz are now available. The array consists of ten antennas: VERA Mizusawa 20 m, VERA Ishigaki 20 m, VERA Iriki 20 m, Usuda 64 m, Yamaguchi 32 m, Tomakomai 11 m, Tsukuba 32 m, Kashima 34 m, VERA Ogasawara 20 m, and Gifu 11 m, the first five of which have 6.7-GHz receiving systems. In summer 2005, we obtained the first fringes at 6.7 GHz, and VLBI images of 12 methanol maser sites including seven that had not previously been imaged with VLBI at this band. In 2006 summer, we obtained phase-reference observations toward several methanol maser sites. © 2008 International Astronomical Union.
  • Hiroshi Nagai, Makoto Inoue, Keiichi Asada, Seiji Kameno, Akihiro Doi
    Astrophys.J.648:148-157,2006 2006年5月12日  
    We present a study of the kinematic and spectral ages of the Gigahertz-Peaked<br /> Spectrum (GPS) source CTD~93. Measurements of the hot spot separation over 8.5<br /> yr show evidence of an increase. The separation rate along the source axis is<br /> 0.34$\pm0.11c$ (H$_{0}$=72 km s$^{-1}$ Mpc$^{-1}$), which results in a<br /> kinematic age of 2200$\pm$700 yr. Assuming that two hot spots are moving apart<br /> at equal speeds, we derive an advance speed of 0.17$\pm0.06c$. The radio lobe<br /> spectra show a high frequency steepening, as expected if energetic electrons<br /> lose energy by synchrotron radiation. The spectral break decreases with the<br /> distance from the hot spot in the northern component of CTD~93. This tendency<br /> is expected from the basic scenario of radio lobe evolution involving particle<br /> acceleration at the hot spots, with the radio lobes populated by high energy<br /> electrons which have leaked from the hot spots. Although a core-jet morphology<br /> for CTD~93 has previously been proposed, these results indicate that the<br /> morphology is similar to that of Compact Symmetric Object (CSO). From the<br /> spectral fits in the northern component we found a break frequency of 3.7 GHz<br /> at the edge of the lobe. The resultant spectral age is $\sim$300 yr assuming<br /> the equipartition magnetic field. This requires the advance speed of 0.26$c$,<br /> which shows a good agreement of the hot spot motion of 0.17$\pm0.06c$. Our<br /> results strongly support the hypothesis that CSOs are young radio sources.
  • Takumi Nagayama, Koji Takeda, Toshihiro Omodaka, Hiroshi Imai, Seiji Kameno, Yoshiaki Sofue, Akihiro Doi, Kenta Fujisawa, Asao Habe, Mareki Honma, Mareki Honma, Noriyuki Kawaguchi, Noriyuki Kawaguchi, Eiji Kawai, Hideyuki Kobayashi, Hideyuki Kobayashi, Yasuhiro Koyama, Yasuhiro Murata, Yasuhiro Murata, Kazuo Sorai, Hiroshi Sudou, Hiroshi Takaba, Sayaka Tamura, Sayaka Tamura, Ken Ichi Wakamatsu
    Publications of the Astronomical Society of Japan 60 1069-1075  
    We present the proper motions of H2O masers in NML Cygni, observed with the Japanese VLBI Network at three epochs spanning 455 d. We detected about 15 maser features at each epoch. Overall, 13 features that were detected at least twice were tracked by their radial velocities and proper motions. The three-dimensional kinematics of the maser features indicate the presence of an expanding outflow. The major axis of the outflow is estimated to be at a position angle of ∼ 108°, and an inclination angle of ∼ 8° with respect to the line of sight. The H2O masers are located between an apparent minimum radius of ∼ 9.6 × 1012 m (64 AU) and a maximum radius of ∼ 3.0 × 1013 m (202AU), where the expansion velocity increases from 12 to 27 km s-1. A comparison with the distributions of SiO, H2O, and OH masers suggests that the outflow of NML Cygni is expanding outside a radius of ∼ 1.5 × 10 13 m (100 AU). This radius corresponds to 6 stellar radii, and is consistent with the radius of the inner boundary for the dust shell. © 2008. Astronomical Society of Japan.

講演・口頭発表等

 28
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共同研究・競争的資金等の研究課題

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