Effect of Local Environment on Galaxy Quenching and Morphology at z < 1

Research Project

Project/Area Number	20K14514
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
Principal Investigator	Kawinwanichakij Lalitwadee 東京大学, カブリ数物連携宇宙研究機構, 特任研究員 (00843004)
Project Period (FY)	2020-04-01 – 2022-03-31
Project Status	Discontinued (Fiscal Year 2021)
Budget Amount *help	¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000) Fiscal Year 2023: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000) Fiscal Year 2022: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000) Fiscal Year 2021: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000) Fiscal Year 2020: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Keywords	Galaxy evolution / Galaxy morphology / Hyper Suprime-Cam / galaxy formation / galaxy evolution / galaxy morphology / structural parameters / size-mass relation / Morphology / Galaxy clusters / Structural parameters / Environments
Outline of Research at the Start	Our catalog of the morphological properties of ~ 7 millions of HSC galaxies will allow us to perform a comprehensive study of the processes that drive morphological changes (from disk-dominated to bulge-dominated) in galaxies. Also, the large sample of HSC galaxies allow us, for the first time, to test the prediction from the recent simulations that intermediate-mass galaxies are able to efficiently grow a disk at low redshift (z < 2), whereas more massive galaxies are unable to form their disk efficiently but mainly form the bulge through galaxy mergers.
Outline of Annual Research Achievements	We utilised the Subaru Hyper Suprime-Cam (HSC) imaging, covering 100 deg^2, to measure structural properties of ~1.5 million galaxies at z < 1. We carefully calibrated our measurements using simulated galaxies to account for various systematic biases. Our test using the simulated galaxies showed that we obtain sizes for galaxies with i< 24.5 mag with 5% accuracy (or better). As a demonstration of science, PI has utilised the size measurements to robustly determine the size-mass relation over the broad range in stellar mass and show that the relations for are better characterised a double-power function: the relation is steeper slope above the pivot mass. Our result from the HSC are in excellent agreements with those from the spaced-based observations, particularly for low-mass galaxies, strongly suggesting that our size measurements are robust and not driven by a systematic bias. The larger sample of massive galaxies than the previous deep surveys enable us to derive the tighter constraint on the size-mass relation for most massive galaxies. The results presented here bridge the gap between the local Universe (z~0) and the high redshift works. PI has submitted the publication with the title “Hyper Suprime-Cam Subaru Strategic Survey: A Mass-Dependent Slope of the Galaxy Size-Mass Relation at z<1” to The Astrophysical Journal. The manuscript has been accepted for publication. We have also made our catalog available to HSC Collaboration.