Distribution of distant galaxy size and luminosity

• Project/Area Number: 22KF0069
• Project/Area Number (Other): 21F21325 (2021-2022)
• Research Category: Grant-in-Aid for JSPS Fellows
• Allocation Type: Multi-year Fund (2023); Single-year Grants (2021-2022)
• Section: 外国
• Review Section: Basic Section 16010:Astronomy-related
• Research Institution: The University of Tokyo
• Principal Investigator: SILVERMAN John 東京大学, カブリ数物連携宇宙研究機構, 教授 (90573030)
• Co-Investigator(Kenkyū-buntansha): YANG LILAN 東京大学, カブリ数物連携宇宙研究機構, 外国人特別研究員
• Project Period (FY): 2023-03-08 – 2024-03-31
• Project Status: Granted (Fiscal Year 2023)
• Budget Amount: ¥2,100,000 (Direct Cost: ¥2,100,000); Fiscal Year 2023: ¥500,000 (Direct Cost: ¥500,000); Fiscal Year 2022: ¥800,000 (Direct Cost: ¥800,000); Fiscal Year 2021: ¥800,000 (Direct Cost: ¥800,000)
• Keywords: galaxy formation / gravitational waves / JWST

Outline of Research at the Start

We are furthering our understanding of the morphological properties of galaxies as a function of wavelength and cosmic time. With JWST, we are observing high redshift galaxies at rest-frame optical wavelengths with exceptional resolution. Secondly, we are investigating the relation between galaxy structure and stellar mass of the brightest cluster galaxies in the Hyper Suprime-Cam Subaru Strategic Program to better understand their growth and impact of their environments.

Outline of Annual Research Achievements

I have used the JSPS Grant-in-Aid to support research on the size-luminosity scaling relation of bright galaxies in the early Universe (i.e., reionization epoch), and understand the mass distribution of the black hole mass-based gravitational wave data. I performed the analysis using the observation data based on the brand-new space telescope JWST. The data is from one of the early release science projects of JWST, and enable us to probe the high redshift galaxy’s morphology and scaling relation for the first time. We found that the size of high redshift galaxies does not vary significantly as a function of wavelength, i.e., from rest-frame UV to optical. We also detected a tentative steeper slope of size-luminosity relation at the rest-frame UV band which indicates that the faint galaxies have extremely small sizes. Furthermore, I also investigated the impact of gravitational lensing on the black hole mass distribution function, and found the current influence from lensing is insignificant. In summary, my main research outcome is the first study of rest-frame optical size-luminosity relation at z>7, and it has made significant contributions understand the galaxy’s morphology and scaling relation in early Universe.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

I have made progress over the past year in investigating the size-luminosity scaling relation of bright galaxies in the early Universe and understanding the mass distribution of the black hole mass-based gravitational wave data. With the brand-new telescope, it enables the investigation of the rest-frame optical size-luminosity scaling relation, and I have gained a better understanding of the properties of early galaxies. The outcomes of my research are evidenced by several publications that have resulted from it in FY2022, including morphological properties and the size-luminosity scaling relation of galaxies, and their wavelength dependence. These findings are significant because they improve our knowledge of understanding galaxy formation and evolution, and its properties at the reionization epoch. Additionally, the achievements of the past year have set a strong foundation for my upcoming research activities.

Strategy for Future Research Activity

For the upcoming year, I plan to continue my research effort on studying the properties of galaxies as a function of wavelength at a wide, using a larger data sample, i.e., from the largest JWST survey COSMOS-Web. I will study the properties of fainter galaxies which are magnified by foreground gravitational lenses such as galaxies and clusters. Additionally, I will use the simulations to further understand galaxy formation and evolution, such as making a direct comparison with our observational results to different simulations, which will provide important clues to verify the assumptions adopted in the simulation.

Research Products

• [Int'l Joint Research] University of California, Los Angeles(米国)