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The Detection of [O III] λ4363 in a Lensed, Dwarf Galaxy at z = 2.59: Testing Metallicity Indicators and Scaling Relations at High Redshift and Low Mass

Gburek, Timothy and Siana, Brian and Alavi, Anahita and Emami, Najmeh and Richard, Johan and Freeman, William R. and Stark, Daniel P. and Snapp-Kolas, Christopher and Lucero, Breanna (2019) The Detection of [O III] λ4363 in a Lensed, Dwarf Galaxy at z = 2.59: Testing Metallicity Indicators and Scaling Relations at High Redshift and Low Mass. Astrophysical Journal, 887 (2). Art. No. 168. ISSN 1538-4357. https://resolver.caltech.edu/CaltechAUTHORS:20191219-112735253

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Abstract

We present Keck/MOSFIRE (Multi-Object Spectrometer for InfraRed Exploration) and Keck/LRIS (Low Resolution Imaging Spectrometer) spectroscopy of A1689-217, a lensed (magnification ~7.9), star-forming (SFR ~ 16 M_☉ yr⁻¹), dwarf (log(M_★/M_☉) = 8.07–8.59) Lyα emitter (EW₀ ~ 138 Å) at z = 2.5918. Dwarf galaxies similar to A1689-217 are common at high redshift and likely responsible for reionization, yet few have been studied with detailed spectroscopy. We report a 4.2σ detection of the electron-temperature-sensitive [O iii] λ4363 emission line and use this line to directly measure an oxygen abundance of 12 + log(O/H) = 8.06 ± 0.12 (~1/4 Z_☉). A1689-217 is the lowest-mass galaxy at z > 2 with an [O iii] λ4363 detection. Using the rest-optical emission lines, we measure A1689-217's other nebular conditions, including electron temperature (T e ([O iii]) ~ 14,000 K), electron density (n e ~ 220 cm⁻³), and reddening (E(B-V) ~ 0.39). We study relations between strong-line ratios and direct metallicities with A1689-217 and other galaxies with [O iii] λ4363 detections at z ~ 0–3.1, showing that the locally calibrated, oxygen-based, strong-line relations are consistent from z ~ 0 to 3.1. We also show additional evidence that the O₃₂ versus R₂₃ excitation diagram can be utilized as a redshift-invariant, direct-metallicity-based, oxygen abundance diagnostic out to z ~ 3.1. From this excitation diagram and the strong-line ratio–metallicity plots, we observe that the ionization parameter at fixed O/H is consistent with no redshift evolution. Although A1689-217 is metal-rich for its M_★ and star formation rate, we find it to be consistent within the large scatter of the low-mass end of the fundamental metallicity relation.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/ab5713DOIArticle
https://arxiv.org/abs/1906.11849arXivDiscussion Paper
ORCID:
AuthorORCID
Gburek, Timothy0000-0002-7732-9205
Siana, Brian0000-0002-4935-9511
Alavi, Anahita0000-0002-8630-6435
Emami, Najmeh0000-0003-2047-1689
Richard, Johan0000-0001-5492-1049
Freeman, William R.0000-0003-3559-5270
Additional Information:© 2019. The American Astronomical Society. Received 2019 June 27; revised 2019 November 4; accepted 2019 November 11; published 2019 December 18. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among 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. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with programs #9289, #11710, #11802, #12201, #12931. This material is based on work supported by the National Science Foundation under grant No. 1617013. Support for program Nos. 12201 and 12931 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Facilities: Keck:I (MOSFIRE - , LRIS) - , HST (WFC3 - , ACS). -
Group:Infrared Processing and Analysis Center (IPAC)
Funders:
Funding AgencyGrant Number
NSFAST-1617013
NASA12201
NASA12931
NASANAS 5-26555
Subject Keywords:Galaxy abundances ; Dwarf galaxies ; Galaxy evolution ; High-redshift galaxies ; Interstellar medium
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Galaxy abundances (574); Dwarf galaxies (416); Galaxy evolution (594); High-redshift galaxies (734); Interstellar medium (847)
Record Number:CaltechAUTHORS:20191219-112735253
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20191219-112735253
Official Citation:Timothy Gburek et al 2019 ApJ 887 168
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100378
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:20 Dec 2019 15:44
Last Modified:20 Dec 2019 15:44

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