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Abstract
We present an analysis of the rest-frame optical spectra of 22 [Oiii]λ4363 detected galaxies in the redshift range 1.65 ≤ z ≤ 7.92 (with 〈z〉 = 4.05) from JWST/NIRSpec
medium-resolution observations taken as part of the EXCELS survey. To
supplement these high-redshift sources, we also consider a sample of 782
local [Oiii]λ4363 detected galaxies
from the DESI Early Data Release. Our analysis demonstrates that many
strong-line calibrations are biased in the early Universe due to the
systematic evolution in ionization conditions with redshift. However,
the recently introduced
R calibration mostly removes the dependence on ionization state and can
be considered a largely redshift-independent calibration. In a similar
spirit, we introduce a new strong-line diagnostic, RNe (using [Oii]λλ3726,3729, [Ne iii]λ3869 and Hγ), which can be used to robustly estimate metallicities when the [Oiii]λ5007 is redshifted out of the wavelength range of JWST/NIRSpec at z > 9.5. We also show that strong-line diagnostics using the [Nii]λ6584
emission line are likely to be biased at high-redshift due to a
moderate enhancement in the average N/O abundance ratios (at fixed O/H)
in these sources. Finally, we discuss the location of our new [Oiii]λ4363 detected galaxies at z
≃ 4 on the mass-metallicity plane and investigate the redshift
evolution of the fundamental metallicity relation (FMR). We find
tentative evidence for an increasing deviation from the FMR at z
> 4 which might indicate fundamental differences in the baryon cycle
at these redshifts. However, more data are required as our
high-redshift constraints are still based on a relatively small sample
of galaxies and the significance of the deviation is strongly dependent
on the assumed form of the fundamental metallicity relation.
Original language | English |
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Pages (from-to) | 1800-1826 |
Number of pages | 26 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 540 |
Issue number | 2 |
Early online date | 21 May 2025 |
DOIs | |
Publication status | Published - 1 Jun 2025 |
Keywords / Materials (for Non-textual outputs)
- galaxies: formation
- galaxies: evolution
- galaxies: high-redshift
- galaxies: ISM
- galaxies: abundances
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Dive into the research topics of 'The JWST EXCELS survey: Probing strong-line diagnostics and the chemical evolution of galaxies over cosmic time using Te-metallicities'. Together they form a unique fingerprint.Projects
- 2 Active
-
Exploring the formation and growth of the first galaxies
Dunlop, J. (Principal Investigator)
31/03/23 → 30/03/28
Project: Research
-
ICE: Inception of the Chemical Elements
Cullen, F. (Principal Investigator)
1/09/22 → 31/08/27
Project: Research