High-resolution Spectroscopic Study of the Structure around Active Galactic Nuclei

2017 Fiscal Year Final Research Report

• Project/Area Number: 26247030
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Astronomy
• Research Institution: Japan Aerospace EXploration Agency
• Principal Investigator: NAKAGAWA Takao 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, 教授 (20202210)
• Co-Investigator(Kenkyū-buntansha): 猿楽 祐樹 京都産業大学, 神山天文台, 主任研究員 (10512147) ; 小林 尚人 東京大学, 大学院理学系研究科(理学部), 准教授 (50280566) ; 和田 武彦 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, 助教 (50312202) ; 片坐 宏一 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, 准教授 (70242097)
• Research Collaborator: KAWAKITA Hideyo 京都産業大学, 神山天文台, 教授 (70356129)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 天文学 / 活動的銀河核 / 分光 / 赤外線

Outline of Final Research Achievements

In order to reveal the structure of the molecular tori, which have be proposed as a key element in the unified scheme of Active Galactic Nuclei (AGNs), we observed the 4.7 micron carbon-monoxide (CO) ro-vibrational absorption band spectra toward several AGNs with the Japanese infrared astronomical satellite AKARI. We detected warm (200-500 K) gas with large column densities and attributed this component to the molecular tori around AGNs. We suggested that the molecular clouds in the tori were heated by X-ray radiation from the central engine of AGNs.
For the future observations of the CO absorption toward high-z AGNs from space borne observatories, we developed a immersion grating for high-resolution spectroscopy in the mid-infrared. We selected CdZnTe as an optimum material for our study, and demonstrated the performance of the immersion grating made of CdZnTe at room temperature.

Free Research Field

赤外線天体物理学