TEMPLATES: Direct Abundance Constraints for Two Lensed Lyman-Break Galaxies

TL;DR

This study uses JWST spectra of two gravitationally lensed galaxies to detect faint auroral lines, enabling direct measurements of their chemical abundances and electron temperatures, thus advancing understanding of galaxy evolution.

Contribution

First direct abundance measurements in high-redshift lensed galaxies using faint auroral lines observed by JWST, demonstrating the potential of combining gravitational lensing with JWST spectroscopy.

Findings

Detected auroral lines in one galaxy, enabling direct abundance calculations.

Established upper limits for auroral lines in the second galaxy.

Found N/O ratio consistent with local galaxies.

Abstract

Using integrated spectra for two gravitationally lensed galaxies from the JWST TEMPLATES Early Release Science program, we analyze faint auroral lines, which provide direct measurements of the gas-phase chemical abundance. For the brighter galaxy, SGAS1723$+$34 ($z = 1.3293$), we detect the [OIII]$\lambda4363$, [SIII]$\lambda6312$, and [OII]$\lambda\lambda$7320,7330 auroral emission lines, and set an upper limit for the [NII]$\lambda5755$ line. For the second galaxy, SGAS1226$+$21 ($z = 2.925$), we do not detect any auroral lines, and report upper limits. With these measurements and upper limits, we constrain the electron temperatures in different ionization zones within both of these galaxies. For SGAS1723$+$34, where auroral lines are detected, we calculate direct oxygen and nitrogen abundances, finding an N/O ratio consistent with observations of nearby ($z\sim 0$) galaxies. These observations highlight the potent combination of JWST and gravitational lensing to measure faint emission lines in individual distant galaxies and to directly study the chemical abundance patterns in those galaxies.