An Independent Test of the Hubble Constant Tension with Time-Delay Cosmography

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K14511
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 16010:Astronomy-related
• Research Institution: The University of Tokyo (2020, 2023); National Astronomical Observatory of Japan (2021-2022)
• Principal Investigator: WONG Kenneth 東京大学, 大学院理学系研究科(理学部), 特任助教 (00794207)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: cosmology / gravitational lensing / extragalactic astronomy

Outline of Final Research Achievements

My research primarily focuses on using strong gravitational lensing (the deflection of light rays by gravity) to study the physical properties of our Universe. By using strongly-lensed images of distant quasars, I worked to constrain the expansion rate of the Universe. This value, called the "Hubble constant", is highly debated, and has important implications for our understanding of physics. I have been working as part of the TDCOSMO collaboration, which has provided the most precise measurement of the Hubble constant using strong gravitational lensing to date. In addition, I have been a leader of the strong lensing working group for the Subaru Hyper Suprime-Cam survey. This large imaging survey provides a great opportunity to search for new strong lenses for a variety of science goals. I have worked on lens searches in the HSC survey using both traditional algorithms and new machine-learning approaches, helping to discover hundreds of new gravitational lenses.

Free Research Field

cosmology; astronomy

Academic Significance and Societal Importance of the Research Achievements

The expansion rate of the Universe has major implications for its age, energy content, and future. My research using gravitational lensing to calculate the expansion rate provides a key independent measurement to check for error in other methods, which have been in tension with each other.