How galaxy evolution diers in dierent environments is one of the intriguing questions in the study of structure formation. While galaxy properties are clearly distinguished in different environments in the local universe, it is still an open issue what causes this environmental dependence of various galaxy properties. To address this question, in this work, we investigate the build-up of passive galaxies over a wide redshift range, from z ~ 2 to z ~ 0.5, focusing on its dependence on galaxy environment. In the UKIDSS/Ultra Deep Survey (UDS) field, we identify high-redshift galaxy cluster candidates within this redshift range. Then, using deep optical and near-infrared data from Subaru and UKIRT available in this field, we analyze and compare the stellar population properties of galaxies in the clusters and in the field. Our results show that the environmental effect on galaxy star-formation properties is a strong function of redshift as well as stellar mass | in the sense that (1) the effect becomes signicant at small redshift, and (2) it is stronger for low-mass (M* < 1010M⊙) galaxies. We have also found that galaxy stellar mass plays a more significant role in determining their star-formation property — i.e., whether they are forming stars actively or not — than their environment throughout the redshift range.

Much of our knowledge about the formation and evolution of high-redshift galaxies has come from studying the absorption signatures they impress on the spectra of background QSOs. The damped Lyman α (DLA) systems, in particular, have proved to be valuable probes of the metallicity and dust at redshifts z ~2-3 in what are the likely progenitors of galaxies like our own. At z ~ 2 we find that the typical metallicity of the universe was 1/15 solar. In addition, we find clear evidence for the existence of trace amounts of interstellar dust in DLA galaxies and show that this is consistent with recent high resolution spectra of DLAs with the Keck telescope, despite claims to the contrary.

We present simulations of the optical-band images of high-redshift galaxies utilizing 845 near-ultraviolet (NUV) images of nearby galaxies obtained through the Galaxy Evolution Explorer (GALEX). We compute the concentration (C), asymmetry (A), Gini (G), and M20 parameters of the GALEX NUV/Sloan Digital Sky Survey r-band images at z ~ 0 and their artificially redshifted optical images at z = 0.9 and 1.6 in order to quantify the morphology of galaxies at local and high redshifts. The morphological properties of nearby galaxies in the NUV are presented using a combination of morphological parameters, in which early- type galaxies are well separated from late-type galaxies in the G–M20, C–M20, A–C, and A–M20 planes. Based on the distribution of galaxies in the A–C and G–M20 planes, we examine the morphological K-correction (i.e., cosmological distance effect and bandshift effect). The cosmological distance effect on the quantitative morphological parameters is found to be significant for early-type galaxies, while late-type galaxies are more greatly affected by the bandshift effect. Knowledge of the morphological K-correction will set the foundation for forthcoming studies on understanding the quantitative assessment of galaxy evolution.