Research Fellow
My research interests and expertise lie in the fields of observational cosmology and astrophysics, with a particular focus on understanding the nature of dark matter and its role in cosmic structure formation. I am best known for my observational studies of galaxy clusters and dark matter utilizing gravitational lensing in combination with complementary datasets. I authored the review article "Cluster-galaxy weak lensing" (Umetsu, K. 2020) in The Astronomy and Astrophysics Review, which provides a comprehensive treatment of the theory, methods, and applications of weak gravitational lensing by galaxy clusters. This article serves as a key reference for both established researchers and newcomers to the field. An updated version, which corrects references and errors in the published article, is available here: [link].
Recently, I coauthored the textbook “一般相対論の基礎から学ぶ 重力レンズと重力波天文学” ("Gravitational Lensing and Gravitational Wave Astronomy from the Foundations of General Relativity"; Nippon Hyoron Sha Co. Ltd., March 2025). In this work, I authored Chapter 3 on gravitational lensing, presenting its theoretical foundations and its applications in observational cosmology with a rigorous approach.