Cosmic Vine: High abundance of massive galaxies and dark matter halos in a forming cluster at z=3.44

The Cosmic Vine is a massive protocluster at z=3.44 in the JWST CEERS field, offering an ideal laboratory for studying the early phases of cluster formation. Using the data from the DAWN JWST Archive, we conducted a comprehensive study on the large-scale structure, stellar mass function (SMF), quiescent members, and dark matter halos in the Cosmic Vine. First, we spectroscopically confirmed 136 galaxies in the Vine at z )>10. Notably, these quiescent members form a tight red sequence on the colour-magnitude diagram, making it one of the earliest red sequences known to date. Third, by constructing the SMFs for both star-forming and quiescent members, we find that both SMFs are top-heavy, with a significantly enhanced quiescent fraction at łog(M_*/ along with an additional 47 galaxies belonging to a diffuse foreground structure at z )=9.5-11.0, the largest sample of quiescent galaxies in overdense environments at z>3, which gives an enhanced quiescent galaxy number density $ that is two to three times above the field level at $łog(M_*/ which we dubbed the Leaf. We identified four subgroups comprising the Cosmic Vine and two subgroups within the Leaf. Second, we identified 11 quiescent members with łog(M_*/ ̊m M_⊙ cMpc -3 ̊m M_⊙ ̊m M_⊙ )>10.5 compared to field counterparts. The stellar mass–size analysis reveals that star-forming members are more compact at higher masses than their field counterparts. Finally, we estimated a halo mass of łog(M_ ̊m h / ̊m M_⊙ )=13.2 / for the protocluster core and łog(M_ ̊m h ̊m M_⊙ )=11.9-12.4 for satellite subgroups. The phase-space analysis indicates that three subgroups are likely infalling to the core. This work reveals a high abundance of massive galaxies and dark matter halos in this forming cluster, demonstrating the accelerated assembly of massive galaxies in massive halos when the Universe was less than 2 billion years old.