2025/06/04 by G. Gozaliasl, Gozaliasl, Ghassem, Lilan Yang +97
Physics and Astronomy · #68T07 #85A40 #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #Baryon #Cosmos (plant) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Galaxy #I.2.6 #J.2 #James Webb Space Telescope #Photometry (optics) #Redshift #Star formation
paper · open access · doi:10.48550/arxiv.2506.04031
published in arXiv (Cornell University) (Cornell University)
openalex publication_date 2025/06/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a comprehensive study of the structural evolution of Brightest Group Galaxies (BGGs) from redshift z ≃ 0.08 to z = 3.7 using the James Webb Space Telescope's 255h COSMOS-Web program. This survey provides deep NIRCam imaging in four filters (F115W, F150W, F277W, F444W) across ∼ 0.54~deg2 and MIRI coverage in ∼ 0.2~deg2 of the COSMOS field. High-resolution NIRCam imaging enables robust size and morphological measurements, while multiwavelength photometry yields stellar masses, SFRs, and Sérsic parameters. We classify BGGs as star-forming and quiescent using both rest-frame NUV--r--J colors and a redshift-dependent specific star formation rate (sSFR) threshold. Our analysis reveals: (1) quiescent BGGs are systematically more compact than their star-forming counterparts and exhibit steeper size--mass slopes; (2) effective radii evolve as Re ∝ (1+z)-α, with α= 1.11 ± 0.07 (star-forming) and 1.40 ± 0.09 (quiescent); (3) star formation surface density (ΣSFR) increases with redshift and shows stronger evolution for massive BGGs (log10(M_∗/M_\odot) ≥ 10.75); (4) in the Σ_*--sSFR plane, a structural transition marks the quenching process, with bulge-dominated systems comprising over 80% of the quiescent population. These results highlight the co-evolution of structure and star formation in BGGs, shaped by both internal and environmental processes, and establish BGGs as critical laboratories for studying the baryonic assembly and morphological transformation of central galaxies in group-scale halos.