• The Bulletin of The Korean Astronomical Society
• /
• v.21
• /
• pp.5.2-5.2
• /
• 1996

• The Bulletin of The Korean Astronomical Society
• /
• v.21
• /
• pp.23.1-23.1
• /
• 1996

• The Bulletin of The Korean Astronomical Society
• /
• v.28 no.2
• /
• pp.60-60
• /
• 2003

• Bulletin of the Korean Space Science Society
• /
• 2007.10a
• /
• pp.92.1-92.1
• /
• 2007

• The Bulletin of The Korean Astronomical Society
• /
• v.31 no.2
• /
• pp.42.2-42.2
• /
• 2006

• The Bulletin of The Korean Astronomical Society
• /
• v.34 no.1
• /
• pp.67.1-67.1
• /
• 2009

• Bulletin of the Korean Space Science Society
• /
• 2009.04a
• /
• pp.37.2-37.2
• /
• 2009

• The Bulletin of The Korean Astronomical Society
• /
• v.40 no.1
• /
• pp.47.2-47.2
• /
• 2015

At local, galaxy properties are well known to be clearly different in different environments. However, it is still an open question how this environment-dependent trend has been shaped. In this presentation, we will show the results of our investigation about the evolution of star-formation properties of galaxies over a wide redshift range, from z~2 to z~0.5, focusing its dependence on their stellar mass and environment. In the UKIDSS/UDS region, we estimated photometric redshifts and stellar population properties, such as stellar masses and star-formation rates, using the deep optical and near-infrared data available in this field. Then, we identified galaxy cluster candidates at z~0.5-2. Through the analysis and comparison of star-formation (SF) properties of galaxies in clusters and in field, we found interesting results regarding the evolution of SF properties of galaxies: (1) regardless of redshifts, stellar mass is a key parameter controlling quenching of star formation in galaxies; (2) At z<1, environmental effects become important at quenching star formation regardless of stellar mass of galaxies; and (3) However, the result of the environmental quenching is prominent only for low mass galaxies (M* < $10^{10}M_{\odot}$) since the star formation in most of high mass galaxies are already quenched at z > 1.

• The Bulletin of The Korean Astronomical Society
• /
• v.42 no.2
• /
• pp.40.2-40.2
• /
• 2017

At local, majority of galaxies in the dense environment, such as galaxy cluster, are red and quiescent with little star-formation (SF) activity. However, a different picture emerges as we go to high redshift: (1) there exist non-negligible fraction of galaxies still forming stars actively even in dense environment, and (2) there is a significant cluster-by-cluster variation in the SF properties, such as quiescent galaxy fraction. In this presentation, we show the results of our study about the variation of quiescent galaxy fraction among high-redshift (z~1) galaxy clusters, based on the multi-object spectroscopic (MOS) observation with IMACS on the Magellan telescope. Our main result is that galaxy clusters which are connected with significant large-scale structure (LSS), well beyond the cluster scale, are more active in their SF activity, i.e., the quiescent galaxy fraction for these clusters is lower compared to the clusters which are detached from LSS.

• The Bulletin of The Korean Astronomical Society
• /
• v.46 no.1
• /
• pp.33.3-34
• /
• 2021

In LCDM universe, large, massive structures, like galaxy clusters, grow through the successive accretion/mergers of smaller structures. Therefore, at high redshift, unlike local, it is expected that there would be plenty of galaxy clusters which are still growing. Here, we report the discovery of a high-redshift (z~1) galaxy cluster which is in its active formation stage. This cluster is well connected to the large scale overdense environment and contains high fraction of star-forming galaxies, providing a good example supporting our previously suggested 'Web-feeding model'.