Dept. of Space Astronomy and Astrophysics

Toyoaki Suzuki

  (鈴木 仁研)

Profile Information

Affiliation
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency
Degree
博士 (理学)(Sep, 2007, 東京大学)

Researcher number
30534599
J-GLOBAL ID
202101020754871070
researchmap Member ID
R000016314

Papers

 70
  • R. Katayama, H. Kaneda, T. Kokusho, K. Morihana, S. Oyabu, T. Suzuki, T. Tsuchikawa, M. Yamagishi
    Astronomy & Astrophysics, 693 A25-A25, Dec 23, 2024  
    Centaurus A (Cen A) is the nearest galaxy hosting an active galactic nucleus (AGN), which produces powerful radio and X-ray jets extending to hundreds of kiloparsecs from the center. At 15 kpc northeast (NE) and 12 kpc southwest (SW) in the halo along the jet from the nucleus of Cen A, dust clouds accompanying the Hα emission are detected. For both NE and SW clouds, past studies suggested that star formation may have been induced through interactions between the AGN jet and the surrounding intergalactic media. For these clouds, we performed dust model fitting of infrared (IR) spectral energy distributions (SEDs) created from the archival data of WISE, Spitzer, and Herschel. Then we compare the IR emission properties of the dust clouds with the far-ultraviolet (UV) emission using the archival data of GALEX/FUV. As a result, we find that the interstellar radiation field intensity G0 (and thus the dust temperature) in the NE cloud suggests star formation activity, while that in the SW cloud does not. The local far-UV intensity and G0 in the NE region are significantly larger than those expected for the far-UV radiation originating from the central region of Cen A and its dust-scattered component, respectively. In contrast, the local far-UV intensity and G0 in the SW region are compatible with them. The polycyclic aromatic hydrocarbon (PAH) emission is detected for both NE and SW clouds. The mass abundance ratios of PAH to dust are similar for both clouds and significantly lower than that in the central region of Cen A. We suggest that the dust clouds and the PAHs in the clouds are associated with the broken ring-like structure of H I gas which is thought to be a remnant of the past gas-rich merger and that shocks by the jet responsible for the middle lobe on the north side may have triggered the star formation in the NE cloud.
  • Takehiko Wada, Kasumi Miyata, Lisa Toyoshima, Masahiro Ueda, Riki Chin, Yoshinori Shohmitsu, Toyoaki Suzuki, Toshihiro Nakaoka
    Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave, 231-231, Aug 23, 2024  
  • Akio K. Inoue, Issei Yamamura, Toyoaki Suzuki, Takao Nakagawa, Hidehiro Kaneda, Hideko Nomura, Tadayuki Kodama, Takehiko Wada, Fumihide Iwamuro, Kentaro Motohara, Yutaka Komiyama, Shinki Oyabu, Yuichi Harikane, Takashi Moriya, Masami Ouchi, Toru Yamada, Shota Notsu
    Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave, 35-35, Aug 23, 2024  
  • 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, Aug 23, 2024  
  • Tsubasa Kondo, Akino Kondo, Katsuhiro L Murata, Takuma Kokusho, Shinki Oyabu, Toyoaki Suzuki, Risako Katayama, Hidehiro Kaneda
    Publications of the Astronomical Society of Japan, 76(5) 1041-1049, Aug 9, 2024  
    Abstract Hydrocarbon dust is one of the dominant components of interstellar dust, which mainly consists of polycyclic aromatic hydrocarbons and aliphatic hydrocarbons. While hydrocarbon dust is thought to be processed in interstellar radiation fields or shocks, detailed processing mechanisms are not completely understood yet. We investigate the processing of hydrocarbon dust by analyzing the relation between the luminosities emitted by hydrocarbon dust and the total infrared luminosities $(L_{\mathrm{IR } })$ for 138 star-forming galaxies at redshift $z \lt 0.3$. Using near-infrared 2.5–5$\, \mu {\rm m}$ spectra obtained with AKARI, we derived the luminosities of the aromatic hydrocarbon feature at 3.3$\, \mu {\rm m}$ ($L_\mathrm{aromatic}$) and the aliphatic hydrocarbon feature at 3.4–3.6$\, \mu {\rm m}$ ($L_\mathrm{aliphatic}$). We also derived $L_\mathrm{IR}$ and the radiation field strength by modeling the spectral energy distributions of the 138 galaxies with AKARI, WISE, and IRAS photometry data. We find that galaxies with higher $L_\mathrm{IR}$ tend to exhibit lower $L_\mathrm{aliphatic}/L_\mathrm{aromatic}$ ratios. Furthermore, we find that there is an anti-correlation between $L_\mathrm{aliphatic}/L_\mathrm{aromatic}$ ratios and the radiation field strength, and also that the galaxies with low $L_\mathrm{aliphatic}/L_\mathrm{aromatic}$ ratios are dominated by merger galaxies. These results support the suggestion that hydrocarbon dust is processed through photodissociation in strong radiation fields and/or shocks during merging processes of galaxies; the $L_\mathrm{aliphatic}/L_\mathrm{aromatic}$ ratio is likely to decrease in such harsh interstellar conditions since the aliphatic bonds are known to be chemically weaker than the aromatic bonds.

Misc.

 7
  • D. Ishihara, H. Kaneda, A. Furuzawa, H. Kunieda, T. Suzuki, B-C. Koo, H-G. Lee, J-J. Lee, T. Onaka
    ASTRONOMY & ASTROPHYSICS, 521 L61, Oct, 2010  
    Aims. We investigate the spatial distribution of dust emission around Tycho's SNR to understand its origin. We distinguish the dust associated with the SNR from that of the surrounding ISM. Methods. We performed mid- to far-infrared imaging observations of the remnant at wavelengths of 9, 15, 18, 24, 65, 90, 140, and 160 mu m using the Infrared Camera and the Far-Infrared Surveyor onboard AKARI. We compared the AKARI images with the Suzaku X-ray image and the (CO)-C-12 image of Tycho's SNR. Results. All the AKARI images except the 9, 140, and 160 mu m band images show a shell-like emission structure with brightness peaks at the northeast (NE) and northwest (NW) boundaries, sharply outlining part of the X-ray shell. The 140 and 160 mu m bands are dominated by cold dust emission from the surrounding ISM near the NE boundary. Conclusions. We conclude that the dust emission at the NE boundary comes from the ambient cloud interacting with the shock front, while the origin of the dust emission at the NW boundary is rather unclear because of the absence of prominent interstellar clouds near the corresponding region. We cannot rule out the possibility that the latter is mostly of an SN ejecta origin.
  • Mitsuyoshi Yamagishi, Hidehiro Kaneda, Daisuke Ishihara, Shinya Komugi, Toyoaki Suzuki, Takashi Onaka
    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN, 62(4) 1085-1092, Aug, 2010  
    We present A KARL near- to far-infrared images of the nearby edge-on spiral galaxy NGC 3079 in 10 photometric bands. The spectral energy distribution consists of continuum emission from dust with a single temperature of 28-33 K together with strong mid-infrared emission features from polycyclic aromatic hydrocarbons (PAHs). We derived dust masses of 5.6 x 10(6) M-circle dot and 1.4 x 10(7) M-circle dot for the central 4 kpc region and the whole galaxy, respectively, and found that the gas-to-dust mass ratio is unusually high in the central region (similar to 1100), and even for the whole galaxy (similar to 860). The ratio of the surface brightness distribution at a wavelength of 7 mu m to that at 11 mu m suggests that the properties of PAHs have spatial variations. The emission from ionized and neutral PAHs is relatively strong in the center and the disk regions, respectively, suggesting a stronger radiation field, and thus relatively active star formation in the center. Yet, the total infrared luminosities of the galaxy indicate rather low star formation rates. These results suggest that NGC 3079 is in an early-phase starburst stage.
  • H. Kaneda, D. Ishihara, T. Suzuki, N. Ikeda, T. Onaka, M. Yamagishi, Y. Ohyama, T. Wada, A. Yasuda
    ASTRONOMY & ASTROPHYSICS, 514 A14, May, 2010  
    Context. The edge-on starburst galaxy M 82 exhibits complicated distributions of gaseous materials in its halo, which include ionized superwinds driven by nuclear starbursts, neutral materials entrained by the superwinds, and large-scale neutral streamers probably caused by a past tidal interaction with M 81. Aims. We investigate detailed distributions of dust grains and polycyclic aromatic hydrocarbons (PAHs) around M 82 to understand their interplay with the gaseous components. Methods. We performed mid- (MIR) and far-infrared (FIR) observations of M 82 with the infrared camera (IRC) and far-infrared surveyor (FIS) onboard AKARI. Results. We obtained new MIR and FIR images of M 82, which reveal both faint extended emission in the halo and very bright emission in the center with signal dynamic ranges as broad as five orders of magnitude for the MIR and three for FIR, respectively. We detected MIR and FIR emission in the regions far away from the disk of the galaxy, reflecting the dust and PAHs in the halo of M 82. Conclusions. We find that the dust and PAHs are contained in both ionized and neutral gas components, implying that they have been expelled into the halo of M 82 by both starbursts and galaxy interaction. In particular, we obtain a tight correlation between the PAH and Ha emission, which provides evidence that the PAHs are well mixed in the ionized superwind gas and flowing out from the disk.
  • H. Kaneda, T. Onaka, I. Sakon, T. Kitayama, Y. Okada, T. Suzuki, D. Ishihara, M. Yamagishi
    The Astrophysical Journal, 716(2,Pt.2) L161-L165, 2010  
    201
  • Hidehiro Kaneda, Mitsuyoshi Yamagishi, Toyoaki Suzuki, Takashi Onaka
    ASTROPHYSICAL JOURNAL LETTERS, 698(2) L125-L128, Jun, 2009  
    We present new far-infrared (FIR) images of the edge-on starburst galaxy NGC 253 obtained with the Far-Infrared Surveyor (FIS) onboard AKARI at wavelengths of 90 mu m and 140 mu m. We have clearly detected FIR dust emission extended in the halo of the galaxy; there are two filamentary emission structures extending from the galactic disk up to 9 kpc in the northern and 6 kpc in the northwestern direction. From its spatial coincidence with the X-ray plasma outflow, the extended FIR emission is very likely to represent outflowing dust entrained by superwinds. The ratios of surface brightness at 90 mu m to that at 140 mu m suggest that the temperatures of the dust in the halo are getting higher in the regions far from the disk, implying that there exist extra dust heating sources in the halo of the galaxy.

Presentations

 87
  • 井上昭雄, 山村一誠, 鈴木仁研, 中川貴雄, 岩室史英, 橋ケ谷武志, 江上英一, Jarron Leisenring, Andre Wong, 金田英宏, 松尾太郎, 本, 原顕太郎, 和田武彦, 野村英子, 守屋尭, 播金優一, 野津翔太, 児玉忠恭, 山田亨, 小宮山裕, 大藪進喜, 大内正己, 宇宙物理学 GDI, 他 GREX-PLUS チーム
    日本天文学会2024年春季年会, Mar 19, 2025
  • 井上昭雄, 播金優一, 野村英子, 守屋尭, 山村一誠, 橋ケ谷武志, 鈴木仁研, 但木謙一, 関根康人, 稲見華恵
    光赤天連タウンミーティング, Dec 27, 2024
  • 和田武彦, 中岡俊裕, 田中陽大, 鈴木仁研, 髙間大輝
    SOIPIX量子イメージング研究会2024, Dec 20, 2024
  • 安藤 麻紀子, 小田切 公秀, 小川 博之, 鈴木 仁研, 関本 裕太郎, JAXA, 松岡 幹也, 上野 藍, 長野 方星
    第68回宇宙科学技術連合講演会, Nov 8, 2024
  • 松岡 幹也, 鈴木 仁研, 上野 藍, 小田切 公秀, 安藤 麻紀子, 関本 裕太郎, 小川 博之, 長野方星
    第68回宇宙科学技術連合講演会, Nov 8, 2024

Professional Memberships

 1

Research Projects

 10