LEGGOS: Direct abundances of N, O, Ne, S, and Ar in five lensed galaxies at Cosmic Noon
astro-ph.GA
Submitted: 2026-09-07
Updated: 2026-09-07
Comments: 19 pages, 5 figures, 4 tables. Submitted to A&A
License: http://creativecommons.org/licenses/by/4.0/
The gist: We present direct T e chemical abundances in five strongly lensed galaxies at Cosmic Noon (2.481 at most z at most 3.625) using JWST/NIRSpec data from the LEGGOS survey.
Terminology
Abstract
We present direct T e chemical abundances in five strongly lensed galaxies at Cosmic Noon (2.481 at most z at most 3.625) using JWST/NIRSpec data from the LEGGOS survey. We measure gas-phase abundances of N, O, S, and Ar in all five galaxies, and Ne in two galaxies. Three galaxies have electron temperature constraints from multiple different ionization zones, and we find that these are broadly consistent with temperature scaling relations observed in both local and high- z galaxies. We find a range of oxygen abundances 8.04 at most 12+ (O/H) at most 8.79 (22 -- 126% Z). The ratios of N/O and Ne/O are consistent with trends observed in local galaxies. We do not observe any evidence for significant N enhancement in our sample, though the youngest galaxy in our sample (SGAS-J1050) has a mildly elevated (N/O) = 1.20 plus or minus 0.08, which we suggest may be driven by a population of young massive stars. The ratios of S/O and Ar/O are generally sub-solar, similar to trends observed in other high- z galaxies. We find that the S/O and Ar/O abundances are sub-solar, consistent with enrichment from core-collapse supernovae (CCSNe). Modeling of the star formation histories of the LEGGOS galaxies supports CCSNe enrichment, as each galaxy shows a recent period of star formation lasting 100 Myr, indicating that type Ia supernovae would not yet have had enough time to contribute significantly to the gas-phase abundances of these galaxies.
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