Chemical Abundance Scaling Relations for Multiple Elements in z ≃ 2–3 Star-forming Galaxies
Abstract
The chemical abundance patterns of gas and stars in galaxies are powerful probes of galaxies' star formation histories and the astrophysics of galaxy assembly but are challenging to measure with confidence in distant galaxies. In this paper, we report the first measurements of the correlation between stellar mass (M_*) and multiple tracers of chemical enrichment (including O, N, and Fe) in individual z ∼ 2–3 galaxies, using a sample of 195 star-forming galaxies from the Keck Baryonic Structure Survey. The galaxies' chemical abundances are inferred using photoionization models capable of reconciling high-redshift galaxies' observed extreme rest-UV and rest-optical spectroscopic properties. We find that the M_*–O/H relation for our sample is relatively shallow, with moderately large scatter, and is offset ∼0.35 dex higher than the corresponding M_*–Fe/H relation. The two relations have very similar slopes, indicating a high level of α-enhancement—O/Fe ≈ 2.2 × (O/Fe)_⊙—across two decades in M_*. The M_*–N/H relation has the steepest slope and largest intrinsic scatter, which likely results from the fact that many z ∼ 2 galaxies are observed near or past the transition from "primary" to "secondary" N production, and may reflect uncertainties in the astrophysical origin of N. Together, these results suggest that z ∼ 2 galaxies are old enough to have seen substantial enrichment from intermediate-mass stars, but are still young enough that Type Ia supernovae have not had time to contribute significantly to their enrichment.
Additional Information
© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 September 18; revised 2021 November 7; accepted 2021 November 9; published 2022 January 31. The data presented in this paper were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership between the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. This work has also been supported in part by the US National Science Foundation (NSF) through grants AST-0908805 and AST-1313472 (ALS and CCS). The authors wish to recognize and acknowledge the significant cultural role and reverence that the summit of Maunakea has within the indigenous Hawaiian community. We are privileged to have had the opportunity to conduct observations from this mountain. Facilities: Keck:I (LRIS - , MOSFIRE) - , Magellan:Baade (FourStar) - , Hale (WIRC) - , Spitzer (IRAC), HST (WFC3). - Software: GalDNA, LINMIX_ERR (Kelly 2007), BPASSv2 (Eldridge & Stanway 2016; Stanway et al. 2016), Cloudy (Ferland et al. 2013), BC03 (Bruzual & Charlot 2003).Attached Files
Published - Allison_L._Strom_et_al_2022_ApJ_925_116.pdf
Accepted Version - 2111.06410.pdf
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Additional details
- Eprint ID
- 113259
- Resolver ID
- CaltechAUTHORS:20220203-318352000
- W. M. Keck Foundation
- AST-0908805
- NSF
- AST-1313472
- NSF
- Created
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2022-02-03Created from EPrint's datestamp field
- Updated
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2022-02-03Created from EPrint's last_modified field
- Caltech groups
- Astronomy Department