GA-NIFS: ISM properties and metal enrichment in a merger-driven starburst during the epoch of reionization probed with JWST and ALMA

Scholtz, J ORCID: 0000-0001-6010-6809, Curti, M, D’Eugenio, F ORCID: 0000-0003-2388-8172, Übler, H ORCID: 0000-0003-4891-0794, Maiolino, R ORCID: 0000-0002-4985-3819, Marconcini, C ORCID: 0000-0002-3194-5416, Smit, R, Perna, M, Witstok, J, Arribas, S, Böker, T ORCID: 0000-0002-5666-7782, Bunker, A J, Carniani, S ORCID: 0000-0002-6719-380X, Charlot, S ORCID: 0000-0003-3458-2275, Cresci, G, Lamperti, I ORCID: 0000-0003-3336-5498, Parlanti, E, Pérez-González, P G, Del Pino, B Rodríguez ORCID: 0000-0001-5171-3930 and Venturi, G ORCID: 0000-0001-8349-3055 (2025) GA-NIFS: ISM properties and metal enrichment in a merger-driven starburst during the epoch of reionization probed with JWST and ALMA. Monthly Notices of the Royal Astronomical Society, 539 (3). pp. 2463-2484. ISSN 0035-8711

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Abstract

We present deep JWST/NIRSpec integral-field spectroscopy (IFS) and ALMA [C ii]158m observations of COS-3018, a star-forming galaxy at z 6.85, as part of the GA-NIFS programme. Both G395H (R 2700) and PRISM (R 100) NIRSpec observations revealed that COS-3018 is comprised of three separate components detected in [O iii]5007, which we dub as Main, North, and East, with stellar masses of 10, 10, 10 . We detect [O iii]5007,4959, [O ii]3727,3729, and multiple Balmer lines in all three components together with [O iii]4363 in the Main and North components. This allows us to measure an interstellar medium temperature of = 1.27 and = 1.6 K with densities of = 1250250 and = 700200 cm, respectively. These deep observations allow us to measure an average metallicity of 12 + log(O/H) = 7.9–8.2 for the three components with the T-method. We do not find any significant evidence of metallicity gradients between the components. Furthermore, we also detect [N ii]6585, one of the highest redshift detections of this emission line. We find that in a small, metal-poor clump 0.2 arcsec west of the North component, N/O is elevated compared to other regions, indicating that nitrogen enrichment originates from smaller substructures, possibly proto-globular clusters. [O iii]5007 kinematics show that this system is merging, which is probably driving the ongoing, luminous starburst.

Item Type:	Article
Uncontrolled Keywords:	galaxies: abundances, galaxies: ISM, galaxies: evolution
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	Oxford University Press
Date of acceptance:	18 March 2025
Date of first compliant Open Access:	2 May 2025
Date Deposited:	02 May 2025 08:48
Last Modified:	02 May 2025 11:15
DOI or ID number:	10.1093/mnras/staf518
URI:	https://researchonline.ljmu.ac.uk/id/eprint/26294

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