报告摘要：The quenching process of galaxies poses a challenge to theoretical models, which struggle to reproduce the quenched fractions from low-redshift to high-redshift. The main issues can be summarized as `over-quenching' of low-mass galaxies at low-redshift, and 'under-quenching' of massive galaxies at high-redshift. By conducting tests on the semi-analytic model GAEA, we find the former challenge is addressed by implementing a milder environmental stripping on hot gas and cold gas; while the latter challenge is resolved by implementing AGN-driven outflows. The model now reproduces a wide range of observational results, including the observed quenched fractions and number densities up to redshift z~3-4. We therefore use the model to investigate quenching mechanisms and large-scale environments of the first massive quenched galaxies. High-redshift massive quiescent galaxies reside in a broad range of environments, from voids, to filamentary structures and knots. Among various indicators of environments, the large-scale over-density can be used as a good predictor of their halo mass at z=0.
主讲人简介：Dr. Lizhi Xie is an assistant researcher in Astrophysics Center, Tianjin Normal University. She received PhD. From National Observatories of China and then moved to Astronomical Observatory of Trieste in Italy for post-doc. As the core member of the GAEA team, she has been developed the modeling related to star formation, black hole seeding, and environmental effects. Her primary research interests include galaxy evolution — including quenching, morphology, gas contents — as well as model developments.
