Prospects for Extending the Mass-Metallicity Relation to Low Mass at High Redshift: A Case Study at z ∼ 1

Abstract

We report J-band MOSFIRE spectroscopy of a low-mass () star-forming galaxy at z = 0.997 showing the detection of [N ii] and [S ii] alongside a strong H line. We derive a gas-phase metallicity of , placing this object in a region of M ∗-Z space that is sparsely populated at this redshift. Furthermore, many existing metallicity measurements in this M ∗-z regime are derived from only [N ii]/H (N2), a diagnostic widely used in high-redshift metallicity studies despite the known strong degeneracy with the ionization parameter and resulting large systematic uncertainty. We demonstrate that even in a regime where [N ii] and [S ii] are at the detection limit and the measurement uncertainty associate..