Environmental effect on the chemical evolution of galaxies revealed with large photometric and spectroscopic data

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K17659
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Astronomy
• Research Institution: The University of Tokyo
• Principal Investigator: YABE Kiyoto 東京大学, カブリ数物連携宇宙研究機構, 特任研究員 (60749480)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 銀河進化 / 化学進化 / 環境効果 / 光赤外天文学

Outline of Final Research Achievements

We investigate the relation between the chemical properties of galaxies and their environment by using a large NIR spectroscopic sample with Subaru/FMOS. We divide our sample into several groups using the stellar mass and the local density, and we apply a spectral stacking analysis in each group. In the obtained combined spectra, Hydrogen, Nitrogen, and Sulfur emission lines are significantly detected. From the ratio of the emission line fluxes, we measure the gas-phase metallicity. We find that the metallicity of galaxies in the higher density region is higher than that in the lower density region at a fixed stellar mass. This may be due to the accretion of the enriched inter-galactic gas that enhances the galaxy metallicity in the high density region.

Free Research Field

天文学

Academic Significance and Societal Importance of the Research Achievements

本研究により銀河の化学的性質と銀河環境との間に密接な関係がある可能性が示された。これらの研究成果は、現在開発中のすばる望遠鏡広視野ファイバー多天体分光器 Prime Focus Spectrograph (PFS)によって、今後さらに発展するものと思われる。本研究は、今後PFSを用いて得られる超大規模分光サンプルによる銀河の化学進化と環境の統計的な研究に先駆けて、重要な知見を得たものとして高い学術的意義を持つ。