Brightest Group Galaxies in COSMOS-Web: Size-mass evolution from z = 3.7 to present

COSMOS-Web Brightest Group Galaxies (BGG) Catalog We construct the BGG catalog by identifying the most massive and luminous galaxy within each group in the COSMOS-Web group sample, as described in Section \ref{app:bgg_selection_detailed} of the accompanying publication. Each group is characterized by its central coordinates (RA_GR, DEC_GR), redshift (Z_GR) from Toni et al. (2025), and a hybrid radius derived from the AMICO detection algorithm. Galaxy membership is defined based on proximity in both angular position and redshift space. Physical properties of the BGGs are cross-matched from the COSMOS2025 multiwavelength catalog (Shuntov et al., submitted) via the unique identifier ID_COSMOS2025_SE++ from the SE++ catalog. Contents of the Catalog The BGG catalog includes the following columns: Group_ID: Unique identifier of the galaxy group RA_GR, DEC_GR: Right ascension and declination of the group center (in degrees) Z_GR: Group redshift Hybrid_radius: Estimated physical radius of the group (arcminutes) ID_COSMOS2025_SE++: BGG identifier from the COSMOS2025 SE++ catalog RA_DETEC, DEC_DETEC: Right ascension and declination of the detected BGG (in degrees) logM: Stellar mass of the BGG in units of \log_{10}(M_\odot) MR: Rest-frame absolute magnitude in the R-band flag_type: Quality or classification flag indicating BGG selection type or potential ambiguity in group membership This catalog supports environmental and structural studies of massive galaxies at intermediate to high redshift (0 < z < 4). It is intended to facilitate comparison across group environments and selection methods within the COSMOS-Web field. For further info please contact [e-mail].