A z = 1.85 galaxy group in CEERS: Evolved, dustless, massive intra-halo light and a brightest group galaxy in the making - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2023

A z = 1.85 galaxy group in CEERS: Evolved, dustless, massive intra-halo light and a brightest group galaxy in the making

Rosemary T Coogan
Emanuele Daddi
David Elbaz
Mark Dickinson
Mauro Giavalisco
Carlos Gómez-Guijarro
Alexander de la Vega
  • Fonction : Auteur
Micaela Bagley
Steven L Finkelstein
Maximilien Franco
Asantha R Cooray
  • Fonction : Auteur
Peter Behroozi
  • Fonction : Auteur
Laura Bisigello
Caitlin M Casey
Laure Ciesla
Paola Dimauro
Alexis Finoguenov
Anton M Koekemoer
  • Fonction : Auteur
Ray A Lucas
  • Fonction : Auteur
Pablo G Pérez-González
  • Fonction : Auteur
L y Aaron Yung
  • Fonction : Auteur
Pablo Arrabal Haro
  • Fonction : Auteur
Jeyhan S Kartaltepe
  • Fonction : Auteur
Shardha Jogee
  • Fonction : Auteur
Casey Papovich
  • Fonction : Auteur
Nor Pirzkal
  • Fonction : Auteur
Stephen M Wilkins
  • Fonction : Auteur

Résumé

We present CEERS JWST/NIRCam imaging of a massive galaxy group at z = 1.85, to explore the early JWST view on massive group formation in the distant Universe. The group contains ≳16 members (including six spectroscopic confirmations) down to log 10 ( M ⋆ / M ⊙ ) = 8.5, including the brightest group galaxy (BGG) in the process of actively assembling at this redshift. The BGG is comprised of multiple merging components extending ∼3.6″ (30 kpc) across the sky. The BGG contributes 69% of the group’s total galactic stellar mass, with one of the merging components containing 76% of the total mass of the BGG and a star formation rate > 1810 M ⊙ yr −1 . Most importantly, we detected intra-halo light (IHL) in several HST and JWST/NIRCam bands, allowing us to construct a state-of-the-art rest-frame UV-NIR spectral energy distribution of the IHL for the first time at this high redshift. This allows stellar population characterisation of both the IHL and member galaxies, as well as the morphology distribution of group galaxies versus their star formation activity when coupled with Herschel data. We created a stacked image of the IHL, giving us a sensitivity to extended emission of 28.5 mag arcsec −2 at rest-frame 1 μm. We find that the IHL is extremely dust poor ( A v ∼ 0), containing an evolved stellar population of log 10 ( t 50 /yr) = 8.8, corresponding to a formation epoch for 50% of the stellar material 0.63 Gyr before z = 1.85. There is no evidence of ongoing star formation in the IHL. The IHL in this group at z = 1.85 contributes ∼10% of the total stellar mass, comparable with what is observed in local clusters. This suggests that the evolution of the IHL fraction is more self-similar with redshift than predicted by some models, challenging our understanding of IHL formation during the assembly of high-redshift clusters. JWST is unveiling a new side of group formation at this redshift, which will evolve into Virgo-like structures in the local Universe.
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Dates et versions

hal-04289529 , version 1 (16-11-2023)

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Rosemary T Coogan, Emanuele Daddi, Aurélien Le Bail, David Elbaz, Mark Dickinson, et al.. A z = 1.85 galaxy group in CEERS: Evolved, dustless, massive intra-halo light and a brightest group galaxy in the making. Astronomy and Astrophysics - A&A, 2023, 677, pp.A3. ⟨10.1051/0004-6361/202346172⟩. ⟨hal-04289529⟩
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