演講資訊

摘要：

How do galaxies assemble their structures over cosmic time, and what role does the environment play in their transformation? In this colloquium, I present a multi-wavelength investigation into galaxy growth over the last 7 billion years (z~1 to 0), leveraging deep CLAUDS+HSC imaging at rest-frame UV (3000 Å) and optical (5000 Å) wavelengths. First, I derived size-mass relations for massive star-forming galaxies (SFGs) and quiescent galaxies (QGs) using single Sérsic fits and examined how their sizes evolve with redshift. I found that the size growth of SFGs is driven largely by the emergence and expansion of their bulges, while QGs grow primarily through minor mergers, accretion, and an influx of newly quenched "newcomer" systems. Next, I explored the role of the environment by separating QGs in cluster cores from those in the field. Despite the dense cluster environment suppressing merger-driven growth and reducing sizes through stripping, both populations show similar size-evolution slopes. This indicates that the observed growth in clusters is dominated by newcomers and infalling galaxies rather than internal structural expansion. Finally, I performed bulge+disk decomposition in both rest-frame UV and optical wavelengths, and measured size-mass relations for each component. Bulges are consistently more compact than disks, and the evolution of bulge-disk components is wavelength-dependent. Bulges in quiescent galaxies show strong UV size growth consistent with ex-situ buildup, while disks evolve more mildly. Together, these results provide a unified view of how galaxies—and their structural components—grow and transform from z~1 to the present, shaped by internal processes, external accretion, and environment.