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| Main Authors: | , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2024
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| Online Access: | https://arxiv.org/abs/2405.00774 |
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| author | Stanton, T. M. Cullen, F. McLure, R. J. Shapley, A. E. Arellano-Córdova, K. Z. Begley, R. Amorín, R. Barrufet, L. Calabrò, A. Carnall, A. C. Cirasuolo, M. Dunlop, J. S. Donnan, C. T. Hamadouche, M. L. Liu, F. -Y. McLeod, D. J. Pentericci, L. Pozzetti, L. Sanders, R. L. Scholte, D. Topping, M. W. |
| author_facet | Stanton, T. M. Cullen, F. McLure, R. J. Shapley, A. E. Arellano-Córdova, K. Z. Begley, R. Amorín, R. Barrufet, L. Calabrò, A. Carnall, A. C. Cirasuolo, M. Dunlop, J. S. Donnan, C. T. Hamadouche, M. L. Liu, F. -Y. McLeod, D. J. Pentericci, L. Pozzetti, L. Sanders, R. L. Scholte, D. Topping, M. W. |
| contents | We present determinations of the gas-phase and stellar metallicities of a sample of 65 star-forming galaxies at $z \simeq 3.5$ 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 ($Z_{\mathrm{g}}$; tracing O/H) via strong optical nebular lines and stellar iron abundances ($Z_{\star}$; tracing Fe/H) from full spectral fitting to the FUV continuum. Our sample spans the stellar mass range $8.5 < \mathrm{log}(M_{\star}/\mathrm{M}_{\odot}) < 10.5$ 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 $\mathrm{Fe/H}\propto M_{\star}^{0.30\pm0.11}$ and $\mathrm{O/H}\propto M_{\star}^{0.32\pm0.09}$. At fixed $M_{\star}$ 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 $\mathrm{(O/Fe)} = 2.65 \pm 0.16 \times \mathrm{(O/Fe)_\odot}$ which appears to be independent of $M_{\star}$. 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 $η\propto M_{\star}^{-0.32}$ 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_00774 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | The NIRVANDELS Survey: the stellar and gas-phase mass-metallicity relations of star-forming galaxies at z = 3.5 Stanton, T. M. Cullen, F. McLure, R. J. Shapley, A. E. Arellano-Córdova, K. Z. Begley, R. Amorín, R. Barrufet, L. Calabrò, A. Carnall, A. C. Cirasuolo, M. Dunlop, J. S. Donnan, C. T. Hamadouche, M. L. Liu, F. -Y. McLeod, D. J. Pentericci, L. Pozzetti, L. Sanders, R. L. Scholte, D. Topping, M. W. Astrophysics of Galaxies We present determinations of the gas-phase and stellar metallicities of a sample of 65 star-forming galaxies at $z \simeq 3.5$ 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 ($Z_{\mathrm{g}}$; tracing O/H) via strong optical nebular lines and stellar iron abundances ($Z_{\star}$; tracing Fe/H) from full spectral fitting to the FUV continuum. Our sample spans the stellar mass range $8.5 < \mathrm{log}(M_{\star}/\mathrm{M}_{\odot}) < 10.5$ 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 $\mathrm{Fe/H}\propto M_{\star}^{0.30\pm0.11}$ and $\mathrm{O/H}\propto M_{\star}^{0.32\pm0.09}$. At fixed $M_{\star}$ 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 $\mathrm{(O/Fe)} = 2.65 \pm 0.16 \times \mathrm{(O/Fe)_\odot}$ which appears to be independent of $M_{\star}$. 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 $η\propto M_{\star}^{-0.32}$ 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. |
| title | The NIRVANDELS Survey: the stellar and gas-phase mass-metallicity relations of star-forming galaxies at z = 3.5 |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2405.00774 |