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

Scholtz, J, Curti, M, D’Eugenio, F, Übler, H, Maiolino, R, Marconcini, C, Smit, R, Perna, M, Witstok, J, Arribas, S, Böker, T, Bunker, A J, Carniani, S, Charlot, S, Cresci, G, Lamperti, I, Parlanti, E, Pérez-González, P G, Del Pino, B Rodríguez and Venturi, G (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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