The Sunburst Arc with JWST. III. An Abundance of Direct Chemical Abundances

The Sunburst Arc with JWST. III. An Abundance of Direct Chemical Abundances

We measure the gas-phase abundances of the elements He, N, O, Ne, S, Ar, and Fe in an individual H ii region known to be leaking Lyman-continuum photons in the Sunburst Arc, a highly magnified galaxy at redshift z = 2.37. We detect the temperature-sensitive auroral lines [S ii ] λλ 4070, 4076, [O ii...

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Main Authors: Brian Welch, T. Emil Rivera-Thorsen, Jane R. Rigby, Taylor A. Hutchison, Grace M. Olivier, Danielle A. Berg, Keren Sharon, Håkon Dahle, M. Riley Owens, Matthew B. Bayliss, Gourav Khullar, John Chisholm, Matthew Hayes, Keunho J. Kim
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
Subjects:
Strong gravitational lensing
Chemical abundances
Abundance ratios
Online Access:https://doi.org/10.3847/1538-4357/ada76c
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Summary:We measure the gas-phase abundances of the elements He, N, O, Ne, S, Ar, and Fe in an individual H ii region known to be leaking Lyman-continuum photons in the Sunburst Arc, a highly magnified galaxy at redshift z = 2.37. We detect the temperature-sensitive auroral lines [S ii ] λλ 4070, 4076, [O iii ] λ 4363, [S iii ] λ 6314, [O ii ] λλ 7320, 7330, and [Ne iii ] λ 3343 in a stacked spectrum of five multiple images of the Lyman-continuum emitter (LCE), from which we directly measure the electron temperature in the low-, intermediate-, and high-ionization zones. We also detect the density-sensitive doublets of [O ii ] λλ 3727, 3730, [S ii ] λλ 6718, 6733, and [Ar iv ] λλ 4713, 4741, which constrain the density in both the low- and high-ionization gas. With these temperature and density measurements, we measure gas-phase abundances with similar rigor as studies of local galaxies and H ii regions. We measure a gas-phase metallicity for the LCE of $12+\mathrm{log}({\rm{O}}/{\rm{H}})=7.97\pm 0.05$ , and find an enhanced nitrogen abundance $\mathrm{log}({\rm{N}}/{\rm{O}})=-0.6{5}_{-0.25}^{+0.16}$ . This nitrogen abundance is consistent with enrichment from a population of Wolf–Rayet stars, additional signatures of which are reported in a companion paper. Abundances of sulfur, argon, neon, and iron are consistent with local low-metallicity H ii regions and low-redshift galaxies. This study represents the most complete chemical abundance analysis of an individual H ii region at Cosmic Noon to date, which enables direct comparisons between local H ii regions and those in the distant Universe.
ISSN:1538-4357

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