Disturbed Cold Gas in Galaxy and Structure Formation
Year: 2025
Type: article
Abstract: The cold gas in the circumgalactic medium (CGM) and its interaction with galaxies remain poorly understood. Strong Mg ii ( λλ 2796, 2803) absorptions seen in background quasar spectra reveal large reservoirs of neutral hydrogen, potentially serving as progenitors of star-forming galaxies at high redshifts. In this study, we search for galaxies in the vicinity of very strong Mg ii absorbers (rest-frame equivalent width W r > 2 Å) with high kinematic velocities (>500 km s −1 ) at 2.0 < z < 6.0. Observations were conducted with the Very Large Telescope/MUSE, JWST/NIRCam, and the Atacama Large Millimeter/submillimeter Array to detect Ly α and nebular emission lines and dust continuum emission. We identify two Ly α emitters associated with a strong Mg ii absorber pair, separated by ∼1000 km s −1 at z ∼ 4.87, in the vicinity of quasar J1306+0356. We observe relative differences in metallicity, dust content, and ionization states in this ultralarge absorption pair system, indicating potential metal and dust transfer within the system. For another strong Mg ii absorber at z = 2.5662 ( W r = 2.638 ± 0.124 Å), toward a second quasar J0305–3150, we detect a dusty star-forming galaxy at a projected distance of D = 38 kpc. This galaxy exhibits prominent He i , [S iii ], and Paschen γ lines, along with significant dust continuum. It has a star formation rate of ∼121 ± 33 M ⊙ yr −1 and likely harbors a rotating disk. These findings tentatively suggest that cold gas at high redshifts fuels disk formation and participates in metal and dust transfer within overdense CGM regions.
Authors: Siwei Zou, Robert A. Simcoe, Patrick Petitjean, Céline Péroux, Jaclyn B. Champagne, Feige Wang, Jinning Liang, Fangzhou Jiang, Zihao Li, Wen Sun, Xiaohui Fan, Jinyi Yang, Luis C. Ho, Xiaojing Lin, Jianan Li, Jianwei Lyu, Lile Wang, Weizhe Liu, Emanuele Paolo Farina, Xiangyu Jin, Cheng Cheng
Institutions: Chinese Academy of Sciences, National Astronomical Observatories, University of Chile, Massachusetts Institute of Technology, Institut d'Astrophysique de Paris, Centre National de la Recherche Scientifique, European Southern Observatory, Aix-Marseille Université, Laboratoire d’Astrophysique de Marseille, University of Arizona, University of Michigan, Peking University, University of Copenhagen, Tsinghua University, NSF NOIRLab
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,400
Funders: National Science Foundation, National Aeronautics and Space Administration, Space Telescope Science Institute, National Radio Astronomy Observatory, Agence Nationale de la Recherche, National Natural Science Foundation of China, Chinese Academy of Sciences, Korea Astronomy and Space Science Institute, National Astronomical Observatory of Japan, National Science and Technology Council, National Institutes of Natural Sciences
OpenAlex ID: W4416766910