Statistical studies of galaxy environments on ISM using the largest CO imaging survey data

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K13593
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 16010:Astronomy-related
• Research Institution: Joetsu University of Education (2020-2021); National Astronomical Observatory of Japan (2018-2019)
• Principal Investigator: Kaneko Hiroyuki 上越教育大学, 大学院学校教育研究科, 特任助教 (10648702)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: 系外銀河 / 分子ガス / 銀河環境

Outline of Final Research Achievements

Galaxies are fundamental structures of the Universe. They are not uniformly distributed in space. They are categorised into three groups: a galaxy cluster, which is made of more than 100 galaxies, a galaxy group, which consists of several to a few tens of galaxies, and an isolated galaxy. While a galaxy cluster and an isolated galaxy have well been studied, the properties of a galaxy group, to which about half of the local galaxies belong, are not understood yet.
I focused on the environmental effect of galaxy groups in this study. The properties of stars, atomic hydrogen, and molecular hydrogen are investigated using large imaging survey data. In a galaxy group environment, the amounts of atomic and molecular gas are similar to isolated galaxies. This result suggests that these gas are not removed from the environment, effective in the galaxy cluster environment. On the other hand, molecular gas distributions are less concentrated toward the centre of a galaxy.

Free Research Field

天文学

Academic Significance and Societal Importance of the Research Achievements

私たちの住む天の川銀河は、局所銀河群、という銀河群の一員です。天の川銀河がどのようにできたのか、を知ろうと思ったとき、天の川銀河の周りの銀河からの影響を調べることも必要です。また、天の川銀河や宇宙全体が今後どう変化していくのか、を理解しようとすると、現在の宇宙で最も一般的な環境である銀河群の研究が重要になります。この研究では、今まであまり調べられていなかった銀河群の分子ガス研究、特に分布がわかる撮像データを使って統計的に調べたことに意義があります。銀河同士は離れて見えますが、天の川銀河のような銀河群では、影響を及ぼしあっていて、分子ガスの分布が銀河の外側の方に偏っている傾向にあるようです。