probing mechanism of quenching of star formation in massive galaxies with a large survey for strong emission-line emitters

2021 Fiscal Year Final Research Report

• Project/Area Number: 17K05386
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Astronomy
• Research Institution: Ehime University
• Principal Investigator: Kajisawa Masaru 愛媛大学, 理工学研究科(理学系), 准教授 (60535334)
• Project Period (FY): 2017-04-01 – 2022-03-31
• Keywords: 銀河進化 / 銀河の星形成史 / 銀河形態

Outline of Final Research Achievements

Using Subaru/Sprime-Cam intermediate-bands data set, we carried out SED analysis and constructed a large sample of galaxies whose star formation was rapidly declining. We investigated their morphology with HST/ACS data, and found that morphological transition from thin disk to thick spheroidal shape occurs at specific SFR ~1 dex lower than the typical values of normal star-forming galaxies, i.e., main sequence. We also found that those galaxies whose SFR was rapidly declining show a systematically high central concentration of asymmetric components in their surface brightness distribution. We carried out optical spectroscopic observations of massive strong Lya emitters at z~3 whose SFR already declined.

Free Research Field

銀河天文学

Academic Significance and Societal Importance of the Research Achievements

銀河の星形成の終焉という銀河の規模の上限を決める銀河進化における重要な過程について、銀河の中心付近で起こる力学的擾乱が密接に関係していることを明らかにした。これは中心における爆発的星形成に伴う超新星爆発や活動銀河中心核などの影響によって星の材料であるガスを銀河から吹き飛ばしたり加熱することで、銀河の星形成が止まる可能性を示唆している。また、このような星形成の減衰に伴って、円盤形状から楕円体形状への銀河の基本的な形態の変化が起こっていることも明らかにした。