The chemical enrichment in the early Universe as probed by JWST via direct metallicity measurements at z ∼ 8

ABSTRACT We analyse the chemical properties of three z∼ 8 galaxies behind the galaxy cluster SMACS J0723.3-7327, observed as part of the Early Release Observations programme of the James Webb Space Telescope. Exploiting [O iii]λ4363 auroral line detections in NIRSpec spectra, we robustly apply the d...

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Bibliographic Details
Published in:Monthly notices of the Royal Astronomical Society Vol. 518; no. 1; pp. 425 - 438
Main Authors: Curti, Mirko, D’Eugenio, Francesco, Carniani, Stefano, Maiolino, Roberto, Sandles, Lester, Witstok, Joris, Baker, William M, Bennett, Jake S, Piotrowska, Joanna M, Tacchella, Sandro, Charlot, Stephane, Nakajima, Kimihiko, Maheson, Gabriel, Mannucci, Filippo, Amiri, Amirnezam, Arribas, Santiago, Belfiore, Francesco, Bonaventura, Nina R, Bunker, Andrew J, Chevallard, Jacopo, Cresci, Giovanni, Curtis-Lake, Emma, Hayden-Pawson, Connor, Jones, Gareth C, Kumari, Nimisha, Laseter, Isaac, Looser, Tobias J, Marconi, Alessandro, Maseda, Michael V, Scholtz, Jan, Smit, Renske, Übler, Hannah, Wallace, Imaan E B
Format: Journal Article
Language:English
Published: London Oxford University Press 01.01.2023
Oxford University Press (OUP): Policy P - Oxford Open Option A
Subjects:
Astrophysics
Chemical properties
Cosmology and Extra-Galactic Astrophysics
Galactic clusters
Galaxies
Gas flow
Line spectra
Metallicity
Physics
Red shift
Space telescopes
Star & galaxy formation
Star formation
Stars & galaxies
galaxies: general
galaxies: abundances
galaxies: evolution
galaxies: ISM
Galaxies: evolution
Galaxies: abundances
Galaxies: ISM
Galaxies: general
ISSN:0035-8711, 1365-2966, 1365-2966
Online Access:Get full text
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Summary:ABSTRACT We analyse the chemical properties of three z∼ 8 galaxies behind the galaxy cluster SMACS J0723.3-7327, observed as part of the Early Release Observations programme of the James Webb Space Telescope. Exploiting [O iii]λ4363 auroral line detections in NIRSpec spectra, we robustly apply the direct Te  method for the very first time at such high redshift, measuring metallicities ranging from extremely metal poor (12 + log(O/H)≈ 7) to about one-third solar. We also discuss the excitation properties of these sources, and compare them with local strong-line metallicity calibrations. We find that none of the considered diagnostics match simultaneously the observed relations between metallicity and strong-line ratios for the three sources, implying that a proper re-assessment of the calibrations may be needed at these redshifts. On the mass–metallicity plane, the two galaxies at z ∼ 7.6 ($\rm log(M_*/M_{\odot }) = 8.1, 8.7$) have metallicities that are consistent with the extrapolation of the mass–metallicity relation at z∼2–3, while the least massive galaxy at z ∼ 8.5 ($\rm log(M_*/M_{\odot }) = 7.8$) shows instead a significantly lower metallicity. The three galaxies show different level of offset relative to the Fundamental Metallicity Relation, with two of them (at z∼ 7.6) being marginally consistent, while the z∼ 8.5 source deviating significantly, being probably far from the smooth equilibrium between gas flows, star formation, and metal enrichment in place at later epochs.
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ISSN:0035-8711
1365-2966
1365-2966
DOI:10.1093/mnras/stac2737