Probing the molecular gas content of galaxies in an over-dense group at z~0.7: A test case for environmental quenching
Abstract
We investigated the impact of group environment on molecular gas reservoirs at an intermediate redshift by observing the CO(2-1) emission from the galaxy group COSMOS-Gr30 at z ∼ 0.7 with the Institut de Radioastronomie Millimetrique (IRAM) NOrthern Extended Millimeter Array (NOEMA) and 30m telescope. This dense environment, located at the intersection of large-scale cosmic web filaments hosts a large (∼ 104 kpc2) ionized gas structure revealed by MUSE. We detect CO emission in four galaxies in the group with a signal-to-noise ratio (S/N) greater than five and derive upper limits for the remaining group members with secure spectroscopic redshifts. Stacked measurements indicate that group galaxies exhibit, on average, molecular gas contents reduced by ∼ 0.5 dex relative to field scaling relations, corresponding to gas fractions that are 20− 40% of those found in typical main-sequence galaxies. Although the uncertainties are significant, this suggests that environmental processes efficiently deplete molecular gas reservoirs in the galaxies of this group. The 30m observations place an upper limit on the molecular gas associated with the extended ionized structure, Mgas < 2 × 1010 M⊙, implying that less than a third of the gas in the intragroup medium is in a cold, star-forming phase. Together, these results show how environmental mechanisms in dense group environments act to remove or suppress molecular gas within galaxies, capturing quenching processes in action.
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BibTeX
@misc{freundlich2026probing,
title = {{Probing the molecular gas content of galaxies in an over-dense group at z~0.7: A test case for environmental quenching}},
author = {Jonathan Freundlich and Benoît Epinat and Thierry Contini and Philippe Salomé and Françoise Combes and Baptiste Jego and Davor Krajnović and Wilfried Mercier and Constanza Muñoz López and Matthieu Béthermin and Leindert Boogaard and Rodrigo Herrera-Camus and Diana Ismail and Fangzhou Jiang and Katarina Kraljic and Florent Renaud and Sandro Tacchella},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2606.26320},
eprint = {2606.26320},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.26320},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Probing the molecular gas content of galaxies in an over-dense group at z~0.7: A test case for environmental quenching
AU - Jonathan Freundlich
AU - Benoît Epinat
AU - Thierry Contini
AU - Philippe Salomé
AU - Françoise Combes
AU - Baptiste Jego
AU - Davor Krajnović
AU - Wilfried Mercier
AU - Constanza Muñoz López
AU - Matthieu Béthermin
AU - Leindert Boogaard
AU - Rodrigo Herrera-Camus
AU - Diana Ismail
AU - Fangzhou Jiang
AU - Katarina Kraljic
AU - Florent Renaud
AU - Sandro Tacchella
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2606.26320
UR - https://arxiv.org/abs/2606.26320
AB - We investigated the impact of group environment on molecular gas reservoirs at an intermediate redshift by observing the CO(2-1) emission from the galaxy group COSMOS-Gr30 at z ∼ 0.7 with the Institut de Radioastronomie Millimetrique (IRAM) NOrthern Extended Millimeter Array (NOEMA) and 30m telescope. This dense environment, located at the intersection of large-scale cosmic web filaments hosts a large (∼ 10^4 kpc^2) ionized gas structure revealed by MUSE. We detect CO emission in four galaxies in the group with a signal-to-noise ratio (S/N) greater than five and derive upper limits for the remaining group members with secure spectroscopic redshifts. Stacked measurements indicate that group galaxies exhibit, on average, molecular gas contents reduced by ∼ 0.5 dex relative to field scaling relations, corresponding to gas fractions that are 20− 40% of those found in typical main-sequence galaxies. Although the uncertainties are significant, this suggests that environmental processes efficiently deplete molecular gas reservoirs in the galaxies of this group. The 30m observations place an upper limit on the molecular gas associated with the extended ionized structure, M_gas < 2 × 10^10 M_⊙, implying that less than a third of the gas in the intragroup medium is in a cold, star-forming phase. Together, these results show how environmental mechanisms in dense group environments act to remove or suppress molecular gas within galaxies, capturing quenching processes in action.
ER -