Understanding starburst phenomena by ALMA wide-frequency band molecular line survey

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03634
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 16010:Astronomy-related
• Research Institution: National Astronomical Observatory of Japan
• Principal Investigator: HARADA Nanase 国立天文台, 科学研究部, 助教 (10785421)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 電波天文学 / 星間化学 / 銀河天文学

Outline of Final Research Achievements

In this study, we target starburst galaxies, where the star formation rate is extremely high. Our aim is to understand what makes this high star formation rate possible, and what is the mechanism to suppress this star formation. To end, we leverage astrochemistry because the molecular compositions are excellent tracers of physical conditions of molecular gas, which is the ingredients of star formation. We utilize the data from the ALMA large program ALCHEMI to derive the molecular composition of the nearby starburst galaxy NGC 253. Our results show several phenomena in NGC 253 related to star formation. We found signs of clouds collisions, which may promote star formation in the future. There are also a large amount of dense gas in NGC 253 compared to our Galactic center, which can explain the high star formation rate in NGC 253. We also found that energies of current and previous generation of stars are heavily influencing the molecular gas, which could hinder future star formation.

Free Research Field

星間化学

Academic Significance and Societal Importance of the Research Achievements

銀河進化の中で多くの銀河が激しい星形成を起こしている段階を通ってきたと考えられる。そのため、その激しい星形成がどうやって起こり、終わっていったのかを知るのは私たちがどのように存在することができるのかを知るストーリーの一部となる。星の形成は分子ガスが材料になるためその分子ガスの理解は星形成に重要である。これまで私たちが住む天の川銀河ではない銀河では分子ガスの質量は簡単に測ることができたが、それ以外の性質を知ることは困難であった。私たちの成果では、その性質をこれまでになく詳しく知ることができた。