Title: Ripe Fruits on the Cosmic Vine: What Massive Quiescent Galaxies at z>3 Reveal about Cluster Formation 

Speaker: Dr. Shuowen Jin (Cosmic Dawn Center (DAWN) in Denmark)

Time: 10:00am, July 23, 2024

Location: 5-516, PMO Xianlin Campus

Abstract: The formation of the brightest cluster galaxies (BCGs) and their progenitors (proto-BCGs) is crucial to our understanding of cluster formation. Therefore, it is important to determine when and how the first generation of massive quiescent galaxies formed in proto-clusters. In this talk, I will report the discovery of the large-scale structure "Cosmic Vine" at z=3.44, and elaborate how it impacts on our understanding of BCG formation. Briefly, we found the two most massive galaxies of the Cosmic Vine to be quiescent with bulge-dominated morphologies. Comparisons with simulations suggest that the Cosmic Vine would form a massive cluster, and the two massive galaxies are likely forming the BCGs. The results unambiguously reveal that massive quiescent galaxies can form in growing large-scale structures at z>3, disfavoring the environmental quenching mechanisms that require a virialized cluster core. Instead, these massive quiescent galaxies are likely quenched by merger-triggered starburst or strong AGN feedback before falling into a cluster core.