A self-consistent direct method for chemical abundances in high-z galaxies with JWST
The unprecedented rest-frame UV and optical coverage provided by James Webb Space Telescope (JWST) enables simultaneous constraints on the electron density (ne ) and temperature (Te ) of ionized gas in galaxies at z > 5. We present a self-consistent direct method based on multiple O iii] (λλ1661,...
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| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
April 2026
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| In: |
Monthly notices of the Royal Astronomical Society
Year: 2026, Volume: 547, Issue: 4, Pages: 1-14 |
| ISSN: | 1365-2966 |
| DOI: | 10.1093/mnras/stag380 |
| Online Access: | Resolving-System, kostenfrei, Volltext: https://doi.org/10.1093/mnras/stag380 Verlag, kostenfrei, Volltext: https://academic.oup.com/mnras/article/547/4/stag380/8502138 
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| Author Notes: | K.Z. Arellano-Córdova, J.E. Méndez-Delgado, S.R. Flury, C. Esteban, K. Kreckel, J. García-Rojas, F. Cullen, L. Carigi, C. Morisset, F.F. Rosales-Ortega, A. Peimbert, T.M. Stanton and D. Scholte |
| Summary: | The unprecedented rest-frame UV and optical coverage provided by James Webb Space Telescope (JWST) enables simultaneous constraints on the electron density (ne ) and temperature (Te ) of ionized gas in galaxies at z > 5. We present a self-consistent direct method based on multiple O iii] (λλ1661, 1666) and [O iii] (λλ4363, 5007) transitions to characterize the physical conditions of the high-ionization zone. This new approach is insensitive to a wide range of ne due to the high critical densities of the O iii] and [O iii] transitions. Applying this technique to six galaxies at z ∼ 5–9, we find electron densities up to ne ∼ 3 × 105 cm−3 and temperatures of Te ∼ 20 000 K in systems at z > 6. Accounting for these self-consistent densities changes the derived Te and modifies the inferred metallicities by up to 0.29 dex relative to previous estimates. We discuss the reported N/O overabundances in our high-z sample, driven by the high N3+ /H+ ratios inferred from the N iv] lines. We point out that a Te -stratification, in which the N3+ zone has a slightly higher Te than Te ([O iii]), could substantially reduce the inferred N/O. Quantitatively, if Te (N3+ ) were 10 per cent higher than Te ([O iii]), this could induce a systematic overestimation of N3+ /O2+ of nearly 50 per cent. Classical N/O diagnostics such as N+ /O+ , due to their critical densities, can significantly impact the inferred N/O abundance in the presence of high-density gas, whereas N2+ /O2+ place these galaxies closer to z ∼ 0 systems in the N/O–O/H plane. While promising, this method accounts for density inhomogeneities but not Te fluctuations, and relies on UV atomic data in the high-ne regime. Future JWST programs will be key to testing its robustness. |
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| Item Description: | Online verfügbar: 28. Februar 2026, Artikelversion: 02. April 2026 Gesehen am 25.06.2026 |
| Physical Description: | Online Resource |
| ISSN: | 1365-2966 |
| DOI: | 10.1093/mnras/stag380 |