Early Results from GLASS-JWST. XXIV. the Mass–Metallicity Relation in Lensed Field Galaxies at Cosmic Noon with NIRISS

We present a measurement of the mass-metallicity relation (MZR) at cosmicnoon, using the JWST near-infrared wide-field slitless spectroscopy obtained bythe GLASS-JWST Early Release Science program. By combining the power of JWSTand the lensing magnification by the foreground cluster A2744, we extend themeasurements of the MZR to the dwarf mass regime at high redshifts. A sample of50 galaxies with several emission lines is identified across two wide redshiftranges of z=1.8-2.3 and 2.6-3.4 in the stellar mass range oflog(M_*/M_⊙)∈ [6.9, 10.0]. The observed slope of MZR is 0.223 ±0.017 and 0.294 ± 0.010 at these two redshift ranges, respectively,consistent with the slopes measured in field galaxies with higher masses. Inaddition, we assess the impact of the morphological broadening on emission linemeasurement by comparing two methods of using 2D forward modeling and lineprofile fitting to 1D extracted spectra. We show that ignoring themorphological broadening effect when deriving line fluxes from grism spectraresults in a systematic reduction of flux by ∼30% on average. Thisdiscrepancy appears to affect all the lines and thus does not lead tosignificant changes in flux ratio and metallicity measurements. This assessmentof the morphological broadening effect using JWST data presents, for the firsttime, an important guideline for future work deriving galaxy line fluxes fromwide-field slitless spectroscopy, such as Euclid, Roman, and the Chinese SpaceStation Telescope.