The NIRVANDELS survey: the stellar and gas-phase mass-metallicity relations of star-forming galaxies at z = 3.5

T. M. Stanton, F. Cullen, R. J. McLure, A. E. Shapley, K. Z. Arellano-Córdova, R. Begley, R. Amorín, L. Barrufet, A. Calabrò, A. C. Carnall, M. Cirasuolo, J. S. Dunlop, C. T. Donnan, M. L. Hamadouche, F. Y. Liu, D. J. McLeod, L. Pentericci, L. Pozzetti, R. L. Sanders, D. ScholteM. W. Topping

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

We present determinations of the gas-phase and stellar metallicities of a sample of 65 star-forming galaxies at z 3.5 using rest-frame far-ultraviolet (FUV) spectroscopy from the VANDELS survey in combination with follow-up rest-frame optical spectroscopy from VLT/KMOS and Keck/MOSFIRE. We infer gas-phase oxygen abundances (Zg; tracing O/H) via strong optical nebular lines and stellar iron abundances (Z*; tracing Fe/H) from full spectral fitting to the FUV continuum. Our sample spans the stellar mass range 8.5 < log(M*/M) < 10.5 and shows clear evidence for both a stellar and gas-phase mass-metallicity relation (MZR). We find that our O and Fe abundance estimates both exhibit a similar mass-dependence, such that Fe/H ∝ M*0.30±0.11 and O/H ∝ M*0.32±0.09. At fixed M* we find that, relative to their solar values, O abundances are systematically larger than Fe abundances (i.e. α-enhancement). We estimate an average enhancement of (O/Fe) = 2.65 ± 0.16 × (O/Fe) which appears to be independent of M*. We employ analytic chemical evolution models to place a constraint on the strength of galactic-level outflows via the mass-outflow factor (η). We show that outflow efficiencies that scale as η ∝ M*−0.32 can simultaneously explain the functional form of of the stellar and gas-phase MZR, as well as the degree of α-enhancement at fixed Fe/H. Our results add further evidence to support a picture in which α-enhanced abundance ratios are ubiquitous in high-redshift star-forming galaxies, as expected for young systems whose interstellar medium is primarily enriched by core-collapse supernovae.

Original languageEnglish
Pages (from-to)3102-3119
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Volume532
Issue number3
DOIs
StatePublished - Aug 1 2024

Bibliographical note

Publisher Copyright:
© 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.

Keywords

  • galaxies: abundances
  • galaxies: evolution
  • galaxies: high redshift

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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