研究者業績

中川 貴雄

ナカガワ タカオ  (Takao Nakagawa)

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
東京大学 大学院理学系研究科 物理学専攻 教授
学位
博士(理学)(東京大学)
修士(理学)(東京大学)

J-GLOBAL ID
200901060914122911
researchmap会員ID
1000363024

外部リンク

委員歴

 3

論文

 395
  • Shusuke Onishi, Takao Nakagawa, Shunsuke Baba, Kosei Matsumoto, Naoki Isobe, Mai Shirahata, Hiroshi Terada, Tomonori Usuda, Shinki Oyabu
    The Astrophysical Journal 2024年11月1日  
  • Hiroto Yanagisawa, Masami Ouchi, Kimihiko Nakajima, Hidenobu Yajima, Hiroya Umeda, Shunsuke Baba, Takao Nakagawa, Minami Nakane, Akinori Matsumoto, Yoshiaki Ono, Yuichi Harikane, Yuki Isobe, Yi Xu, Yechi Zhang
    The Astrophysical Journal 974(2) 180-180 2024年10月1日  
    Abstract We investigate the physical origins of the Balmer decrement anomalies in GS-NDG-9422 and RXCJ2248-ID galaxies at z ∼ 6 whose Hα/Hβ values are significantly smaller than 2.7, the latter of which also shows anomalous Hγ/Hβ and Hδ/Hβ values beyond the errors. Because the anomalous Balmer decrements are not reproduced under the Case B recombination, we explore the nebulae with optical depths smaller and larger than the Case B recombination by physical modeling. We find two cases quantitatively explaining the anomalies: (1) density-bounded nebulae that are opaque only up to around Lyγ–Ly8 transitions and (2) ionization-bounded nebulae partly/fully surrounded by optically thick excited H i clouds. The case of (1) produces more Hβ photons via Lyγ absorption in the nebulae, requiring fine tuning in optical depth values, while this case helps ionizing photon escape for cosmic reionization. The case of (2) needs the optically thick excited Hi clouds with N 2 ≃ 1012−1013 cm−2, where N 2 is the column density of the hydrogen atom with the principal quantum number of n = 2. Interestingly, the high N 2 values qualitatively agree with the recent claims for GS-NDG-9422 with the strong nebular continuum requiring a number of 2s-state electrons and for RXCJ2248-ID with the dense ionized regions likely coexisting with the optically thick clouds. While the physical origin of the optically thick excited H i clouds is unclear, these results may suggest gas clouds with excessive collisional excitation caused by an amount of accretion and supernovae in the high-z galaxies.
  • Takao Nakagawa, Hideo Matsuhara, Umi Enokidani, Toyoaki Suzuki, Shunsuke Baba, Yasuhiro Hirahara, Hidehiro Kaneda, Ryoichi Koga, Yuan Li, Biao Zhao, Daiki Takama, Hiroshi Sasago, Takehiko Wada, Toshihiro Nakaoka, Taiki Eda, Ryota Kakihara, Yoshinori Shohmitsu, Takuya Hosobata, Noboru Ebizuka, Yutaka Yamagata, Shota Notsu, Hideko Nomura
    Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 236-236 2024年8月23日  
  • Shunsuke Nakagawa, Chinathip Narongphun, Zamba Leonel, Hari Shrestha, Isami Kato, Emino Fukumoto, Rodrigo Cordova, Victor Hugo Schulz, Necmi Cihan Örger, Kei Sano, Takao Nakagawa, Koji Takimoto, Shuji Matsuura, Kohji Tsumura, Aoi Takahashi, Daisuke Nakayama, Akimasa Ojika, Rin Sato, Keenan A. A. Chatar, Yukihisa Otani, Ezra Fielding, Kentaro Hayashida, Hayato Tanaka, Eyoas E. Areda, Bastien B. A. Morelle, Hisataka Kawasaki, Umi Enokidani, Reynel Josue Galindo Rosales, Karaki Shohei, Ichiro Jikuya
    Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 117-117 2024年8月23日  
  • Hisataka Kawasaki, Eyoas E. Areda, Hideo Matsuhara, Hirokazu Masui, Kohji Takimoto, Bastien B. A. Morelle, Shuji Matsuura, Takao Nakagawa, Umi Enokidani, Yuki Hirose, Kei Sano
    Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 116-116 2024年8月23日  

MISC

 675

共同研究・競争的資金等の研究課題

 49

● 専任大学名

 1
  • 専任大学名
    東京大学(University of Tokyo)