【開催】 合同C棟N507 天文専攻大輪講室（変更されることがあります。）
Spatially resolved stellar mass buildup and quenching of massive disk galaxies at z ~ 0-1
For decades, studies of galaxy evolution have relied on the global properties. Some scaling relations and evolutionary trends in the global scale have been revealed from these studies. Among the others, studies of the galaxy global properties revealed that at redshift between ~2 and 0, majority of galaxies were undergoing quenching (i.e. shutting down of star formation). It is also revealed that star-forming galaxies are confined in a tight star-formation main sequence (SFMS, a SFR-stellar mass relation) over wide cosmic time (from z=0 to ~6). Nowadays, there is a growing interest on studying spatially resolved properties of galaxies with various techniques and instruments (such as integral field spectroscopy (IFS), grism spectroscopy, and narrow band imaging) to reveal evolution of the spatially resolved properties of galaxies and get more insight on physical mechanism of the galaxy evolution. In this presentation, I will introduce results of our study on the spatially resolved properties of massive disk galaxies at z~0 and z~1 using our established spatially resolved SED fitting technique. Using this technique, we could spatially resolve the properties of galaxies at wide redshift range with the same manner for each redshift bin. From this study, we found a fundamental sub-galactic (~1 kpc scale) SFMS, namely spatially resolved SFMS, which hold in both of our z~1 and z~0 samples. Evolution of this relation shows a decreasing local sSFR and increasing prominence of a “flattening” at high-mass end from z~1 star-forming to z~0 quiescent samples which indicates a decreasing sSFR in disk and the formation and growth of bulge. We also studied evolution of the radial profiles of SFR, stellar mass, and sSFR and made an empirical model that could connect the observed radial profiles at z~1 and z~0. Overall, our study revealed that massive disk galaxies tend to build their stellar mass and quench their star-formation from central region first, then propagates toward outskirt, i.e. inside-out stellar mass buildup and quenching.
【The Colloquium Committee in 2018】
Kenji Toma (toma<at>astr.tohoku.ac.jp)