Issue |
A&A
Volume 696, April 2025
|
|
---|---|---|
Article Number | A83 | |
Number of page(s) | 9 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/202452652 | |
Published online | 07 April 2025 |
Deep kiloparsec view of the molecular gas in a massive star-forming galaxy at cosmic noon
1
Departamento de Astronomía, Universidad de Concepción, Barrio Universitario, Concepción, Chile
2
Millenium Nucleus for Galaxies (MINGAL), Concepción, Chile
3
Max-Planck-Institut für Extraterrestische Physik, Giessenbachstr. 1, 85748 Garching, Germany
4
Cosmic Dawn Center (DAWN), Copenhagen, Denmark
5
DTU-Space, Technical University of Denmark, Elektrovej 327, DK-2800 Kgs. Lyngby, Denmark
6
Department of Astronomy, University of Maryland, College Park, MD 20742, USA
7
Purple Mountain Observatory, Chinese Academy of Sciences, 10 Yuanhua Road, Nanjing 210023, People’s Republic of China
8
INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, I-35122 Padova, Italy
⋆ Corresponding author; searriagada2018@udec.cl
Received:
17
October
2024
Accepted:
13
February
2025
We present deep (∼20 hr), high-angular resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations of the CO (4 − 3) and [CI] (1 − 0) transitions, along with the rest-frame 630 μm dust continuum, in BX610–a massive, main-sequence galaxy at the peak epoch of cosmic star formation (z = 2.21). Combined with deep Very Large Telescope (VLT) SINFONI observations of the Hα line, we characterize the molecular gas and star formation activity on kiloparsec scales. Our analysis reveals that the excitation of the molecular gas, as traced by the L′CO(4−3)/L′[CI](1−0) line luminosity ratio, decreases with increasing galactocentric radius. While the line luminosity ratios in the outskirts are similar to those typically found in main-sequence galaxies at z ∼ 1, the ratios in the central regions of BX610 are comparable to those observed in local starbursts. There is also a giant extra-nuclear star-forming clump in the southwest of BX610 that exhibits high star formation activity, molecular gas abundance, and molecular gas excitation. Furthermore, the central region of BX610 is rich in molecular gas (Mmol/M⋆ ≈ 1); however, at the current level of star formation activity, such molecular gas is expected to be depleted in ∼450 Myr. This, along with recent evidence for rapid inflow toward the center, suggests that BX610 may be experiencing an evolutionary phase often referred to as wet compaction, which is expected to lead to central gas depletion and subsequent inside-out quenching of star formation activity.
Key words: galaxies: evolution / galaxies: high-redshift / galaxies: ISM / galaxies: star formation
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.