Speaker
Description
It is important to find and study protoclusters in the distant Universe during their formative stages in order to understand the formation and evolution of present-day galaxy clusters. In the pre-JWST era, protocluster candidates were primarily identified up to z ≲ 7, limited by optical wavelength coverage and survey area. With deep JWST
near-infrared surveys such as CEERS and JADES have enabled the identification of protocluster candidates at z > 7. By taking advantage of JWST COSMOS-Web’s near-infrared sensitivity, spatial resolution, and wide survey area, Wu et al. (2025) identified seven z ≈ 9–10 protocluster candidates using COSMOS-Web DR0.5 (FOV: 0.27 deg²). In this work, we present an extended search for high-redshift (z ≈ 9–10) protocluster candidates using the full DR1.0 dataset (FOV:0.54 deg²). We apply F115W-dropout color selection and spectral energy distribution (SED) fitting to isolate high-redshift galaxy candidates, and compute local overdensities to identify protocluster regions. The identification of protoclusters at z > 9 provides new constraints on the formation and early evolution of the most massive structures in the Universe.