Early Results from GLASS-JWST. VI. Extreme Rest-optical Equivalent Widths Detected in NIRISS Wide Field Slitless Spectroscopy
Vulcani, B.; Brammer, G.; Treu, T.; Castellano, M.; Jones, T.; Pentericci, L.; Trenti, M.; Grillo, C.; Rosati, P.; Wang, X.; Fontana, A.; Vanzella, E.; Marchesini, D.; Scarlata, C.; Glazebrook, K.; Willott, C.; Nanayakkara, T.; Calabrò, A.; Morishita, T.; Mercurio, A.; Henry, A.; Mason, C.; Boyett, K.; Bradac, M.; Mascia, S.; Bergamini, P.; Leethochawalit, N.; Roberts-Borsani, G.; Strait, V.; Acebron, A.
Australia, Italy, Thailand, Denmark, United States, Slovenia, Canada
Abstract
Wide Field Slitless Spectroscopy (WFSS) provides a powerful tool for detecting strong line emission in star-forming galaxies (SFGs) without the need for target preselection. As part of the GLASS-JWST Early Release Science (ERS) program, we leverage the near-infrared wavelength capabilities of NIRISS (1-2.2 μm) to observe rest-optical emission lines out to z ~ 3.4, to a depth and with a spatial resolution higher than ever before (Hα to z < 2.4; [O III]+Hβ to z < 3.4). In this Letter we constrain the rest-frame [O III]λ5007 equivalent width (EW) distribution for a sample of 76 1 < z < 3.4 SFGs in the A2744 Hubble Frontier Field and determine an abundance fraction of extreme emission line galaxies with EW > 750Å in our sample to be 12%. We determine a strong correlation between the measured Hβ and [O III]λ5007 EWs, supporting that the high [O III]λ5007 EW objects require massive stars in young stellar populations to generate the high-energy photons needed to doubly ionize oxygen. We extracted spectra for objects up to 2 mag fainter in the near-infrared than previous WFSS studies with the Hubble Space Telescope. Thus, this work clearly highlights the potential of JWST/NIRISS to provide high-quality WFSS data sets in crowded cluster environments.