Welcome to Sukyoung K. Yi's group (GEM) homepage!

이석영 교수의 은하진화 연구 그룹 홈페이지에 오신것을 환영합니다.


Science Goal 연구 목표

We aim to understand the formation and evolution of galaxies. 우리 그룹의 연구 목표는 은하의 형성과 진화과정을 이해하는 것입니다.

News 소식

  • The 2024 NewCluster workshop will be held on 26 - 30 August, 2024 in Yonsei university, Seoul, and Gangneung, Korea
  • The 2023 GEM Fall workshop will be held on 20 - 21 October, 2023 in Ramada hotel, Jeju, Korea
  • The 2022 GEM Winter workshop will be held on 8 - 11 January, 2023 in WE hotel, Jeju, Korea
  • The 2020 GEM 2nd workshop will be held on 19 - 21 August, 2020 in Yonsei University, Seoul, Korea (Cancelled)
  • The 2020 GEM workshop will be held on 14 - 17 January, 2020 in Gyeongju, Korea
  • Minjung Park's paper has been introduced by AAS Nova (23 September 2019).
  • Dr. Sandro Tacchella will visit GEM (8-11 July, 2019)
  • The 2019 GEM - CASCADE workshop will be held on 1 - 4 July, 2019 in Jeju, Korea
  • The 2018 GEM workshop will be held on 2 - 4 July, 2018 in Kangnung, Korea
  • Dr. Scott Croom, Dr. Julia Bryant and Dr. Warrick Couch will visit GEM (10-13 Apr 2017)
  • Dr. Barbara Cantinella and Dr. Luca Cortese at ICRAR are visiting GEM (1-15 Apr 2017)
  • SAMI workshop will be held at KASI. (12 Apr 2017)
  • Environment workshop wiil be held. (3 Apr 2017)

Recent Paper 최근 논문

Star Formation History and Transition Epoch of Cluster Galaxies Based on the Horizon-AGN Simulation

Seyoung Jeon, Sukyoung K. Yi, Yohan Dubois, Aeree Chung, Julien Devriendt, San Han, Ryan A. Jackson, Taysun Kimm, Christophe Pichon, and Jinsu Rhee


Cluster galaxies exhibit substantially lower star formation rates than field galaxies today, but it is conceivable that clusters were sites of more active star formation in the early universe. Herein, we present an interpretation of the star formation history (SFH) of group/cluster galaxies based on the large-scale cosmological hydrodynamic simulation, Horizon-AGN. We find that massive galaxies in general have small values of e-folding timescales of star formation decay (i.e., “mass quenching”) regardless of their environment, while low-mass galaxies exhibit prominent environmental dependence. In massive host halos (i.e., clusters), the e-folding timescales of low-mass galaxies are further decreased if they reside in such halos for a longer period of time. This “environmental quenching” trend is consistent with the theoretical expectation from ram pressure stripping. Furthermore, we define a “transition epoch” as where cluster galaxies become less star-forming than field galaxies. The transition epoch of group/cluster galaxies varies according to their stellar and host-cluster halo masses. Low-mass galaxies in massive clusters show the earliest transition epoch of ∼7.6 Gyr ago in lookback time. However, this decreases to ∼5.2 Gyr for massive galaxies in low-mass clusters. Based on our findings, we can describe a cluster galaxy’s SFH with regard to the cluster halo-to-stellar mass ratio.

국문 요약

근우주에서 은하단 은하의 현저히 낮은 별 생성률이 과거에는 오히려 일반적인 필드 은하보다 높았음을 Horizon-AGN 시뮬레이션을 활용하여 확인함. 환경 효과에 의한 별 생성 억제는 약 50~80억년전부터 효과를 발휘하였고, 따라서 현재 우리가 이해하고 있는 은하단 환경의 특성은 우주 나이의 최근 절반에만 해당함을 의미함. 또한 암흑헤일로-은하별질량 비율을 이용하여 별 생성 특성을 잘 추정할 수 있음을 보임.



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