Early Results from GLASS-JWST. IV. Spatially Resolved Metallicity in a Low-mass z similar to 3 Galaxy with NIRISS

Xin Wang*, Tucker Jones, Benedetta Vulcani, Tommaso Treu, Takahiro Morishita, Guido Roberts-Borsani, Matthew A. Malkan, Alaina Henry, Gabriel Brammer, Victoria Strait, Marusa Bradac, Kristan Boyett, Antonello Calabro, Marco Castellano, Adriano Fontana, Karl Glazebrook, Patrick L. Kelly, Nicha Leethochawalit, Danilo Marchesini, P. SantiniM. Trenti, Lilan Yang

*Corresponding author for this work

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Abstract

We report the first gas-phase metallicity map of a distant galaxy measured with the James Webb Space Telescope (JWST). We use the NIRISS slitless spectroscopy acquired by the GLASS Early Release Science program to spatially resolve the rest-frame optical nebular emission lines in a gravitationally lensed galaxy at z = 3.06 behind the A2744 galaxy cluster. This galaxy (dubbed GLASS-Zgrad1) has stellar mass similar to 10(8.6)M(circle dot), instantaneous star formation rate similar to 8.6 M-circle dot yr(-1) (both corrected for lensing magnification), and global metallicity one-fourth solar. From its emission-line maps ([O III], H beta, H gamma, [Ne III], and [O II]), we derive its spatial distribution of gas-phase metallicity using a well-established forward-modeling Bayesian inference method. The exquisite resolution and sensitivity of JWST/NIRISS, combined with lensing magnification, enable us to resolve this z similar to 3 dwarf galaxy in greater than or similar to 50 resolution elements with sufficient signal, an analysis hitherto not possible. We find that the radial metallicity gradient of GLASS-Zgrad1 is strongly inverted (i.e., positive): Delta log (O/H)/Delta r = 0.165 +/- 0.023 dex kpc(-1). This measurement is robust at greater than or similar to 4 - sigma confidence level against known systematics. This positive gradient may be due to tidal torques induced by a massive nearby (similar to 15 kpc projected) galaxy, which can cause inflows of metal-poor gas into the central regions of GLASS-Zgrad1. These first results showcase the power of JWST wide-field slitless spectroscopic modes to resolve the mass assembly and chemical enrichment of low-mass galaxies in and beyond the peak epoch of cosmic star formation (z greater than or similar to 2). Reaching masses less than or similar to 10(9) M-circle dot at these redshifts is especially valuable to constrain the effects of galactic feedback and environment and is possible only with JWST's new capabilities.

Original languageEnglish
Article numberL16
JournalAstrophysical Journal Letters
Volume938
Issue number2
Number of pages9
ISSN2041-8205
DOIs
Publication statusPublished - 18 Oct 2022

Keywords

  • STAR-FORMING GALAXIES
  • ABUNDANCE GRADIENTS
  • GEOSTATISTICAL ANALYSIS
  • SURVEY DESIGN
  • RESOLUTION
  • STELLAR
  • CENSUS
  • DISCS
  • MAPS

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