Developing Environments: Formation and Quenching at Cosmic Noon Traced by the Large-scale Distribution of Gas and Galaxies

@misc{khoram2026developing,
  title = {{Developing Environments: Formation and Quenching at Cosmic Noon Traced by the Large-scale Distribution of Gas and Galaxies}},
  author = {Amir H. Khoram and Sirio Belli and Trevor Mendel and Letizia Bugiani and Matteo Sapori and Andrew B. Newman and Hossein Hatamnia and Finn Giddings and Rebecca L. Davies and Olga Cucciati and Bianca Poggianti and Amirnezam Amiri and Anita Zanella and Tianmu Gao and Gabriel Maheson and Stefano Sotira and Caterina Liboni and Giulia Papini},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.00190},
  eprint = {2611.00190},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.00190},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Developing Environments: Formation and Quenching at Cosmic Noon Traced by the Large-scale Distribution of Gas and Galaxies
AU  - Amir H. Khoram
AU  - Sirio Belli
AU  - Trevor Mendel
AU  - Letizia Bugiani
AU  - Matteo Sapori
AU  - Andrew B. Newman
AU  - Hossein Hatamnia
AU  - Finn Giddings
AU  - Rebecca L. Davies
AU  - Olga Cucciati
AU  - Bianca Poggianti
AU  - Amirnezam Amiri
AU  - Anita Zanella
AU  - Tianmu Gao
AU  - Gabriel Maheson
AU  - Stefano Sotira
AU  - Caterina Liboni
AU  - Giulia Papini
PY  - 2026
DA  - 2026/11/01
PB  - arXiv
DO  - 10.48550/arxiv.2611.00190
UR  - https://arxiv.org/abs/2611.00190
AB  - Environmental density correlates with galaxy properties in the local Universe, but how and when these trends emerge is unclear: at cosmic noon, large-scale structures are still assembling and galaxies quench rapidly for debated reasons. We study how the formation and quenching histories of massive galaxies at 1.7<z<3.5 depend on environment, using two independent tracers: galaxy number density (δ_#) from COSMOS-Web and intergalactic neutral hydrogen (δ_HI, cool gas) from LATIS Lyα tomography. We combine 139 Blue Jay JWST/NIRSpec galaxies with 57 DAWN JWST Archive prism spectra in COSMOS, deriving stellar masses, star formation histories, dust attenuation, and Na\,{\sc d} outflow rates from joint spectro-photometric \texttt{Prospector} fits. In massive quiescent galaxies, the formation-to-quenching interval increases with density. AGN and Na\,{\sc d} outflows are confined to δ_#<0.5 and elevated Lyα absorption (δ_HI>1), mostly in massive quiescent galaxies showing both. About 65\% of the sample follows a correlation between the tracers; two outlier regions stand out. A galaxy-rich, gas-poor region (δ_#>2, δ_HI<1) coincides with one of the most massive Hyperion protocluster cores, where the gas is plausibly fully ionized; its quiescent galaxies formed earlier and lack significant AGN activity and outflows. A galaxy-poor, gas-rich region (δ_#<1, δ_HI>1), within 60 cMpc of the densest Hyperion cores, hosts rapidly quenched galaxies with a high incidence of AGN and outflows. This \emph{developing environment}, distinct from both mature protoclusters and the field, likely traces massive halos still assembling. Galaxy counts alone cannot capture the environment at cosmic noon: jointly mapping galaxies and cool gas is crucial to understand how environment regulates gas accretion, star formation, and quenching.
ER  -