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Arxiv: The Sunburst Arc with JWST: III. An Abundance of Direct Chemical Abundances Published: 5/10/2024 8:48:16 PM Updated: 5/14/2024 4:29:32 PM

Paper abstract: We measure the gas-phase abundances of the elements He, N, O, Ne, S, Ar, andFe in the Lyman-continuum emitting region of the Sunburst Arc, a highlymagnified galaxy at redshift z=2.37. We detect the temperature-sensitiveauroral lines [SII]\lambda\lambda4069,4076, [OII]\lambda\lambda7320,7330,[SIII]\lambda6312, [OIII]\lambda4363, and [NeIII]\lambda3343 in a stackedspectrum of 5 multiple images of the Lyman-continuum emitter (LCE), from whichwe directly measure the electron temperature in the low, intermediate, and highionization zones. We also detect the density-sensitive doublets of[OII]\lambda\lambda3727,3729, [SII]\lambda\lambda6717,6731, and[ArIV]\lambda\lambda4713,4741, which constrain the density in both the low-and high-ionization gas. With these temperature and density measurements, wemeasure gas-phase abundances with similar rigor as studies of local galaxies.We measure a gas-phase metallicity for the LCE of12+\log(\textrm{O}/\textrm{H}) = 7.97 \pm 0.05, and find an enhanced nitrogenabundance \log(\textrm{N}/\textrm{O}) = -0.65^{+0.16}_{-0.25}. This nitrogenabundance is consistent with enrichment from a population of Wolf-Rayet stars,additional signatures of which are reported in a companion paper. Abundances ofsulfur, argon, neon, and iron are consistent with local low-metallicity HIIregions and low-redshift galaxies. This study represents the most completechemical abundance analysis of a galaxy at Cosmic Noon to date, which enablesdirect comparisons between local HII regions and those in the distant universe.