Brightest group galaxies in COSMOS-Web: Evolution of the size-mass relation since z = 3.7

Ghassem Gozaliasl; Lilan Yang; Jeyhan S. Kartaltepe; Greta Toni; Fatemeh Abedini; Hollis B. Akins; Natalie Allen; Rafael C. Arango-Toro; Arif Babul; Caitlin M. Casey; Nima Chartab; Nicole E. Drakos; Andreas L. Faisst; Alexis Finoguenov; Carter Flayhart; Maximilien Franco; Zohreh Ghaffari; Gavin Leroy; Aryana Haghjoo; Hosein Haghi; Santosh Harish; Akram Hasani Zonoozi; Günther Hasinger; Hossein Hatamnia; Olivier Ilbert; Shuowen Jin; Darshan Kakkad; Atousa Kalantari; Ali Ahmad Khostovan; Anton M. Koekemoer; Maarit Korpi-Lagg; Clotilde Laigle; Daizhong Liu; Georgios Magdis; Matteo Maturi; Henry Joy Mccracken; Jed Mckinney; Nicolas Mcmahon; Wilfried Mercier; Bahram Mobasher; Lauro Moscardini; Jason Rhodes; Brant E. Robertson; Louise Paquereau; Annagrazia Puglisi; Rasha M. Samir; Sogol Sanjaripour; Mark Sargent; Zahra Sattari; Diana Scognamiglio; Nick Scoville; Marko Shuntov; David B. Sanders; Sina Taamoli; Sune Toft; Eleni Vardoulaki

doi:10.1051/0004-6361/202556085

Brightest group galaxies in COSMOS-Web: Evolution of the size-mass relation since z = 3.7

Ghassem Gozaliasl^*
, Lilan Yang
, Jeyhan S. Kartaltepe
, Greta Toni
, Fatemeh Abedini
, Hollis B. Akins
, Natalie Allen^*
, Rafael C. Arango-Toro
, Arif Babul
, Caitlin M. Casey
, Nima Chartab
, Nicole E. Drakos
, Andreas L. Faisst
, Alexis Finoguenov
, Carter Flayhart
, Maximilien Franco
, Zohreh Ghaffari
, Gavin Leroy
, Aryana Haghjoo
, Hosein Haghi

Santosh Harish, Akram Hasani Zonoozi, Günther Hasinger, Hossein Hatamnia, Olivier Ilbert, Shuowen Jin, Darshan Kakkad, Atousa Kalantari, Ali Ahmad Khostovan, Anton M. Koekemoer, Maarit Korpi-Lagg, Clotilde Laigle, Daizhong Liu, Georgios Magdis, Matteo Maturi, Henry Joy Mccracken, Jed Mckinney, Nicolas Mcmahon, Wilfried Mercier, Bahram Mobasher, Lauro Moscardini, Jason Rhodes, Brant E. Robertson, Louise Paquereau, Annagrazia Puglisi, Rasha M. Samir, Sogol Sanjaripour, Mark Sargent, Zahra Sattari, Diana Scognamiglio, Nick Scoville, Marko Shuntov, David B. Sanders, Sina Taamoli, Sune Toft, Eleni Vardoulaki

^*Corresponding author for this work

University of Helsinki
Rochester Institute of Technology
University of Bologna
Institute for Advanced Studies in Basic Sciences, Zanjan
University of Texas at Austin
Cosmic Dawn Center
CNRS
Indian Institute of Science Bangalore
California Institute of Technology
University of Hawai'i at Hilo
Université Paris-Saclay
Osservatorio Astronomico di Trieste
Durham University
University of California at Riverside
University of Bonn
Technische Universität Dresden
University of Hertfordshire
University of Kentucky
Space Telescope Science Institute
Aalto University
Institut d’Astrophysique de Paris
CAS - Purple Mountain Observatory
Heidelberg University
University of California at Santa Cruz
University of Southampton
National Research Institute of Astronomy and Geophysics
Swiss Federal Institute of Technology Lausanne
University of Geneva
University of Hawai'i at Mānoa
University of Copenhagen
Karl Schwarzschild Observatory

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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, and F444W) in ∼ 0.54 deg², allowing robust size and morphological measurements for ∼1700 BGGs spanning ∼12 Gyr of cosmic history. High-resolution imaging enables consistent measurement of galaxy sizes in the rest-frame optical (red to near-infrared; ∼6000–8000 Å) across cosmic time through redshift-dependent filter selection. We classified BGGs as star-forming and quiescent using both rest-frame NUV–r–J colors and redshift-dependent specific star formation rate (sSFR) thresholds. Our structural analysis reveals that quiescent BGGs are systematically more compact than their star-forming counterparts across all redshifts, exhibiting steeper size–mass slopes (α_QG ∼ 0.6–1.2 vs. α_SF ∼ 0.0–0.3). The effective radius evolves as R_e ∝ (1 + z)^−α, with α = 0.96 ± 0.07 for star-forming BGGs and α = 1.24 ± 0.09 for quiescent BGGs, indicating stronger size growth in quenched systems. The corresponding growth factor at fixed stellar mass (log M_∗ = 10.7) from z = 3.7 to z = 0.08 is ∼ 4.4 for star-forming and ∼6.6 for quiescent BGGs. The intrinsic scatter in the size–mass relation increases toward higher redshift for both populations, reaching ∼0.3–0.4 dex at z > 2, reflecting greater structural diversity in the early universe. Compared to field galaxies, BGGs show systematically smaller sizes at fixed stellar mass, particularly among quiescent systems, highlighting environmental effects on galaxy structure. We further compare the evolution of the quiescent fraction, the Sérsic 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.

Original language	English
Article number	A129
Journal	Astronomy and Astrophysics
Volume	703
Number of pages	20
ISSN	0004-6361
DOIs	https://doi.org/10.1051/0004-6361/202556085
Publication status	Published - 2025

Keywords

Galaxies: clusters: general
Galaxies: evolution
Galaxies: groups: general
Galaxies: high-redshift
Galaxies: star formation
Galaxies: structure

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Gozaliasl, G., Yang, L., Kartaltepe, J. S., Toni, G., Abedini, F., Akins, H. B., Allen, N., Arango-Toro, R. C., Babul, A., Casey, C. M., Chartab, N., Drakos, N. E., Faisst, A. L., Finoguenov, A., Flayhart, C., Franco, M., Ghaffari, Z., Leroy, G., Haghjoo, A., ... Vardoulaki, E. (2025). Brightest group galaxies in COSMOS-Web: Evolution of the size-mass relation since z = 3.7. Astronomy and Astrophysics, 703, Article A129. https://doi.org/10.1051/0004-6361/202556085

@article{e46fc0420fc641fb98045c696a173b0a,

title = "Brightest group galaxies in COSMOS-Web: Evolution of the size-mass relation since z = 3.7",

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{\textquoteright}s 255-hour COSMOS-Web program. This survey provides deep NIRCam imaging in four filters (F115W, F150W, F277W, and F444W) in ∼ 0.54 deg2, allowing robust size and morphological measurements for ∼1700 BGGs spanning ∼12 Gyr of cosmic history. High-resolution imaging enables consistent measurement of galaxy sizes in the rest-frame optical (red to near-infrared; ∼6000–8000 {\AA}) across cosmic time through redshift-dependent filter selection. We classified BGGs as star-forming and quiescent using both rest-frame NUV–r–J colors and redshift-dependent specific star formation rate (sSFR) thresholds. Our structural analysis reveals that quiescent BGGs are systematically more compact than their star-forming counterparts across all redshifts, exhibiting steeper size–mass slopes (αQG ∼ 0.6–1.2 vs. αSF ∼ 0.0–0.3). The effective radius evolves as Re ∝ (1 + z)−α, with α = 0.96 ± 0.07 for star-forming BGGs and α = 1.24 ± 0.09 for quiescent BGGs, indicating stronger size growth in quenched systems. The corresponding growth factor at fixed stellar mass (log M∗ = 10.7) from z = 3.7 to z = 0.08 is ∼ 4.4 for star-forming and ∼6.6 for quiescent BGGs. The intrinsic scatter in the size–mass relation increases toward higher redshift for both populations, reaching ∼0.3–0.4 dex at z > 2, reflecting greater structural diversity in the early universe. Compared to field galaxies, BGGs show systematically smaller sizes at fixed stellar mass, particularly among quiescent systems, highlighting environmental effects on galaxy structure. We further compare the evolution of the quiescent fraction, the S{\'e}rsic 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.",

keywords = "Galaxies: clusters: general, Galaxies: evolution, Galaxies: groups: general, Galaxies: high-redshift, Galaxies: star formation, Galaxies: structure",

author = "Ghassem Gozaliasl and Lilan Yang and Kartaltepe, \{Jeyhan S.\} and Greta Toni and Fatemeh Abedini and Akins, \{Hollis B.\} and Natalie Allen and Arango-Toro, \{Rafael C.\} and Arif Babul and Casey, \{Caitlin M.\} and Nima Chartab and Drakos, \{Nicole E.\} and Faisst, \{Andreas L.\} and Alexis Finoguenov and Carter Flayhart and Maximilien Franco and Zohreh Ghaffari and Gavin Leroy and Aryana Haghjoo and Hosein Haghi and Santosh Harish and Zonoozi, \{Akram Hasani\} and G{\"u}nther Hasinger and Hossein Hatamnia and Olivier Ilbert and Shuowen Jin and Darshan Kakkad and Atousa Kalantari and Khostovan, \{Ali Ahmad\} and Koekemoer, \{Anton M.\} and Maarit Korpi-Lagg and Clotilde Laigle and Daizhong Liu and Georgios Magdis and Matteo Maturi and Mccracken, \{Henry Joy\} and Jed Mckinney and Nicolas Mcmahon and Wilfried Mercier and Bahram Mobasher and Lauro Moscardini and Jason Rhodes and Robertson, \{Brant E.\} and Louise Paquereau and Annagrazia Puglisi and Samir, \{Rasha M.\} and Sogol Sanjaripour and Mark Sargent and Zahra Sattari and Diana Scognamiglio and Nick Scoville and Marko Shuntov and Sanders, \{David B.\} and Sina Taamoli and Sune Toft and Eleni Vardoulaki",

note = "Publisher Copyright: {\textcopyright} The Authors 2025.",

year = "2025",

doi = "10.1051/0004-6361/202556085",

language = "English",

volume = "703",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

Gozaliasl, G, Yang, L, Kartaltepe, JS, Toni, G, Abedini, F, Akins, HB, Allen, N, Arango-Toro, RC, Babul, A, Casey, CM, Chartab, N, Drakos, NE, Faisst, AL, Finoguenov, A, Flayhart, C, Franco, M, Ghaffari, Z, Leroy, G, Haghjoo, A, Haghi, H, Harish, S, Zonoozi, AH, Hasinger, G, Hatamnia, H, Ilbert, O, Jin, S, Kakkad, D, Kalantari, A, Khostovan, AA, Koekemoer, AM, Korpi-Lagg, M, Laigle, C, Liu, D, Magdis, G, Maturi, M, Mccracken, HJ, Mckinney, J, Mcmahon, N, Mercier, W, Mobasher, B, Moscardini, L, Rhodes, J, Robertson, BE, Paquereau, L, Puglisi, A, Samir, RM, Sanjaripour, S, Sargent, M, Sattari, Z, Scognamiglio, D, Scoville, N, Shuntov, M, Sanders, DB, Taamoli, S, Toft, S & Vardoulaki, E 2025, 'Brightest group galaxies in COSMOS-Web: Evolution of the size-mass relation since z = 3.7', Astronomy and Astrophysics, vol. 703, A129. https://doi.org/10.1051/0004-6361/202556085

TY - JOUR

T1 - Brightest group galaxies in COSMOS-Web

T2 - Evolution of the size-mass relation since z = 3.7

AU - Gozaliasl, Ghassem

AU - Yang, Lilan

AU - Kartaltepe, Jeyhan S.

AU - Toni, Greta

AU - Abedini, Fatemeh

AU - Akins, Hollis B.

AU - Allen, Natalie

AU - Arango-Toro, Rafael C.

AU - Babul, Arif

AU - Casey, Caitlin M.

AU - Chartab, Nima

AU - Drakos, Nicole E.

AU - Faisst, Andreas L.

AU - Finoguenov, Alexis

AU - Flayhart, Carter

AU - Franco, Maximilien

AU - Ghaffari, Zohreh

AU - Leroy, Gavin

AU - Haghjoo, Aryana

AU - Haghi, Hosein

AU - Harish, Santosh

AU - Zonoozi, Akram Hasani

AU - Hasinger, Günther

AU - Hatamnia, Hossein

AU - Ilbert, Olivier

AU - Jin, Shuowen

AU - Kakkad, Darshan

AU - Kalantari, Atousa

AU - Khostovan, Ali Ahmad

AU - Koekemoer, Anton M.

AU - Korpi-Lagg, Maarit

AU - Laigle, Clotilde

AU - Liu, Daizhong

AU - Magdis, Georgios

AU - Maturi, Matteo

AU - Mccracken, Henry Joy

AU - Mckinney, Jed

AU - Mcmahon, Nicolas

AU - Mercier, Wilfried

AU - Mobasher, Bahram

AU - Moscardini, Lauro

AU - Rhodes, Jason

AU - Robertson, Brant E.

AU - Paquereau, Louise

AU - Puglisi, Annagrazia

AU - Samir, Rasha M.

AU - Sanjaripour, Sogol

AU - Sargent, Mark

AU - Sattari, Zahra

AU - Scognamiglio, Diana

AU - Scoville, Nick

AU - Shuntov, Marko

AU - Sanders, David B.

AU - Taamoli, Sina

AU - Toft, Sune

AU - Vardoulaki, Eleni

PY - 2025

Y1 - 2025

N2 - 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, and F444W) in ∼ 0.54 deg2, allowing robust size and morphological measurements for ∼1700 BGGs spanning ∼12 Gyr of cosmic history. High-resolution imaging enables consistent measurement of galaxy sizes in the rest-frame optical (red to near-infrared; ∼6000–8000 Å) across cosmic time through redshift-dependent filter selection. We classified BGGs as star-forming and quiescent using both rest-frame NUV–r–J colors and redshift-dependent specific star formation rate (sSFR) thresholds. Our structural analysis reveals that quiescent BGGs are systematically more compact than their star-forming counterparts across all redshifts, exhibiting steeper size–mass slopes (αQG ∼ 0.6–1.2 vs. αSF ∼ 0.0–0.3). The effective radius evolves as Re ∝ (1 + z)−α, with α = 0.96 ± 0.07 for star-forming BGGs and α = 1.24 ± 0.09 for quiescent BGGs, indicating stronger size growth in quenched systems. The corresponding growth factor at fixed stellar mass (log M∗ = 10.7) from z = 3.7 to z = 0.08 is ∼ 4.4 for star-forming and ∼6.6 for quiescent BGGs. The intrinsic scatter in the size–mass relation increases toward higher redshift for both populations, reaching ∼0.3–0.4 dex at z > 2, reflecting greater structural diversity in the early universe. Compared to field galaxies, BGGs show systematically smaller sizes at fixed stellar mass, particularly among quiescent systems, highlighting environmental effects on galaxy structure. We further compare the evolution of the quiescent fraction, the Sérsic 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.

AB - 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, and F444W) in ∼ 0.54 deg2, allowing robust size and morphological measurements for ∼1700 BGGs spanning ∼12 Gyr of cosmic history. High-resolution imaging enables consistent measurement of galaxy sizes in the rest-frame optical (red to near-infrared; ∼6000–8000 Å) across cosmic time through redshift-dependent filter selection. We classified BGGs as star-forming and quiescent using both rest-frame NUV–r–J colors and redshift-dependent specific star formation rate (sSFR) thresholds. Our structural analysis reveals that quiescent BGGs are systematically more compact than their star-forming counterparts across all redshifts, exhibiting steeper size–mass slopes (αQG ∼ 0.6–1.2 vs. αSF ∼ 0.0–0.3). The effective radius evolves as Re ∝ (1 + z)−α, with α = 0.96 ± 0.07 for star-forming BGGs and α = 1.24 ± 0.09 for quiescent BGGs, indicating stronger size growth in quenched systems. The corresponding growth factor at fixed stellar mass (log M∗ = 10.7) from z = 3.7 to z = 0.08 is ∼ 4.4 for star-forming and ∼6.6 for quiescent BGGs. The intrinsic scatter in the size–mass relation increases toward higher redshift for both populations, reaching ∼0.3–0.4 dex at z > 2, reflecting greater structural diversity in the early universe. Compared to field galaxies, BGGs show systematically smaller sizes at fixed stellar mass, particularly among quiescent systems, highlighting environmental effects on galaxy structure. We further compare the evolution of the quiescent fraction, the Sérsic 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.

KW - Galaxies: clusters: general

KW - Galaxies: evolution

KW - Galaxies: groups: general

KW - Galaxies: high-redshift

KW - Galaxies: star formation

KW - Galaxies: structure

U2 - 10.1051/0004-6361/202556085

DO - 10.1051/0004-6361/202556085

M3 - Journal article

AN - SCOPUS:105022843650

SN - 0004-6361

VL - 703

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A129

ER -

Brightest group galaxies in COSMOS-Web: Evolution of the size-mass relation since z = 3.7

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