J/A+A/703/A129 COSMOS-Web Brightest Group Galaxy (BGG) Cat. (Gozaliasl+, 2025)
Brightest group galaxies in COSMOS-Web:
Evolution of the size-mass relation since z = 3.7.
Gozaliasl G., Yang L., Kartaltepe J., Toni G., Abedini F., Akins B.H.,
Allen N., Arango-Toro C.R., Babul A., Casey M.C., Chartab N., Drakos E.N.,
Faisst L.A., Finoguenov A., Flayhart C., Franco M., Ghaffari Z., Leroy G.,
Haghjoo A., Haghi H., Harish S., Zonoozi A.H., Hasinger G., Hatamnia H.,
Ilbert O., Jin S., Kakkad D., Kalantari A., Khostovan A.A., Koekemoer M.A.,
Korpi-Lagg M., Laigle C., Liu D., Magdis G., Maturi M., McCracken H.J.,
McKinney J., McMahon N., Mercier W., Mobasher B., Moscardini L., Rhodes J.,
Robertson E.B., Paquereau L., Puglisi A., Samir M.R., Sanjaripour S.,
Sargent M., Sattari Z., Scognamiglio D., Scoville N., Shuntov M.,
Sanders B.D., Taamoli S., Toft S., Vardoulaki E.
<Astron. Astrophys. 703, A129 (2025)>
=2025A&A...703A.129G 2025A&A...703A.129G (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, group ; Redshifts ; Magnitudes ; Stars, masses ;
Photometry
Keywords: galaxies: clusters: general - galaxies: evolution -
galaxies: high-redshift - galaxies: star formation -
galaxies: structure
Abstract:
We present the first 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 255-hour COSMOS-Web program. This
survey provides deep NIRCam imaging in four filters (F115W, F150W,
F277W, F444W) in ∼0.54deg2, enabling robust size and morphological
measurements for ∼1700 BGGs spanning ∼12Gyr of cosmic history.
High-resolution imaging enables consistent size measurements in the
rest-frame optical across cosmic time through redshift-dependent
filter selection.
We classified BGCS as star-forming and quiescent using both
rest-frame NUV-r-J colors and redshift-dependent specific star
formation rate thresholds. Our structural analysis shows:
quiescent BGGs are more compact than star-forming counterparts across
all redshifts, with steeper size-mass slopes (alphaQG∼0.6-1.2 vs.
alphaSF∼0.0-0.3); the effective radius evolves as Re ∝
(1+z)-alpha, with alpha=0.96±0.07 for star-forming and
alpha=1.24±0.09 for quiescent BGGs, implying stronger size growth in
quenched systems; the corresponding growth factor at logM*=10.7 from
z=3.7 to z=0.08 is ∼4.4 for star-forming and ∼6.6 for quiescent BGGs.
the scatter in the size-mass relation increases toward high
redshift, reaching ∼0.3-0.4 dex at z>2, reflecting greater structural
diversity. Compared to field galaxies, BGGs are systematically smaller
at fixed mass, especially among quiescent systems, highlighting
environmental effects. We further compare the evolution of the
quiescent fraction, the Sersic index, and ellipticity with those of
field galaxies, finding consistent trends that reinforce our main
conclusions. These results establish the foundation for understanding
how group-scale environments shape the structural evolution of central
galaxies and provide crucial constraints for models of galaxy
formation in intermediate-mass dark matter halos.
Description:
This catalog lists Brightest Group Galaxies (BGGs) identified in the
COSMOS-Web survey. BGGs are defined as the most massive galaxy in each
detected group, with stellar masses and photometry derived from the
COSMOS2025 catalog. Galaxy groups were identified using the AMICO
detection algorithm applied to deep JWST NIRCam COSMOS-Web imaging.
The catalog provides positions, redshifts, stellar masses, magnitudes,
and classification flags for each BGG.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 105 1678 COSMOS-Web BGG catalog
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See also:
J/ApJS/224/24 : The COSMOS2015 catalog (Laigle+, 2016)
J/ApJS/268/10 : The value-added COSMOS2020 catalog (Rusakov+, 2023)
J/A+A/697/A197 : COSMOS-Web deep galaxy group catalog up to z=3.7
(Toni+, 2025)
https://cosmos2025.iap.fr : COSMOS2025 home page
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- GroupID [1/1816] Unique identifier of the
galaxy group (1)
6- 14 F9.5 deg RAdeg Right Ascension of group center (J2000)
16- 24 F9.7 deg DEdeg Declination of group center (J2000)
26- 29 F4.2 --- zG Group redshift
31- 36 A6 --- RhybG Estimated group hybrid radius
(250kpc or 500kpc)
38- 43 I6 --- SEpp COSMOS2025 SE++ source identifier
45- 62 F18.14 deg RABdeg Right Ascension of detected BGG (J2000)
64- 81 F18.16 deg DEBdeg Declination of detected BGG (J2000)
83- 90 F8.5 [Msun] logM log10 Stellar mass of BGG (2)
92-100 F9.5 mag RMAG Rest-frame absolute R-band magnitude
102-105 A4 --- Ftype Classification flag/quality indicator,
mag or mass (3)
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Note (1): Group detections follow the AMICO probabilistic algorithm.
Note (2): Stellar masses are derived from multiwavelength photometry in
COSMOS2025.
Note (3): Flags indicate type or confidence of BGG identification.
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Acknowledgements:
From Ghassem Gozaliasl, ghassem.gozaliasl(at)aalto.fi
Based on COSMOS-Web survey data obtained with JWST, and on COSMOS2025
multiwavelength catalog.
(End) Patricia Vannier [CDS] 11-Sep-2025