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

Wang, Xin and Jones, Tucker and Vulcani, Benedetta and Treu, Tommaso and Morishita, Takahiro and Roberts-Borsani, Guido and Malkan, Matthew A. and Henry, Alaina and Brammer, Gabriel and Strait, Victoria and Bradač, Maruša and Boyett, Kristan and Calabrò, Antonello and Castellano, Marco and Fontana, Adriano and Glazebrook, Karl and Kelly, Patrick L. and Leethochawalit, Nicha and Marchesini, Danilo and Santini, P. and Trenti, M. and Yang, Lilan (2022) Early Results from GLASS-JWST. IV. Spatially Resolved Metallicity in a Low-mass z ∼ 3 Galaxy with NIRISS. Astrophysical Journal Letters, 938 (2). LArt. No. 16. ISSN 2041-8205. doi:10.3847/2041-8213/ac959e.

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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 ∼10^(8.6) M_⊙, instantaneous star formation rate ∼8.6 M_⊙ yr⁻¹ (both corrected for lensing magnification), and global metallicity one-fourth solar. From its emission-line maps ([O ɪɪɪ], Hβ, Hγ, [Ne ɪɪɪ], and [O ɪɪ]), 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 ∼ 3 dwarf galaxy in ≳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): Δlog(O/H)/Δr = 0.165 ± 0.023 dex kpc⁻¹. This measurement is robust at ≳ - σ confidence level against known systematics. This positive gradient may be due to tidal torques induced by a massive nearby (∼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 ≳ 2). Reaching masses ≲ 10⁹ M_⊙ at these redshifts is especially valuable to constrain the effects of galactic feedback and environment and is possible only with JWST's new capabilities.

Item Type:Article
Related URLs:
URLURL TypeDescription
Wang, Xin0000-0002-9373-3865
Jones, Tucker0000-0001-5860-3419
Vulcani, Benedetta0000-0003-0980-1499
Treu, Tommaso0000-0002-8460-0390
Morishita, Takahiro0000-0002-8512-1404
Roberts-Borsani, Guido0000-0002-4140-1367
Malkan, Matthew A.0000-0001-6919-1237
Henry, Alaina0000-0002-6586-4446
Brammer, Gabriel0000-0003-2680-005X
Strait, Victoria0000-0002-6338-7295
Bradač, Maruša0000-0001-5984-0395
Boyett, Kristan0000-0003-4109-304X
Calabrò, Antonello0000-0003-2536-1614
Castellano, Marco0000-0001-9875-8263
Fontana, Adriano0000-0003-3820-2823
Glazebrook, Karl0000-0002-3254-9044
Kelly, Patrick L.0000-0003-3142-997X
Leethochawalit, Nicha0000-0003-4570-3159
Marchesini, Danilo0000-0001-9002-3502
Santini, P.0000-0002-9334-8705
Trenti, M.0000-0001-9391-305X
Yang, Lilan0000-0002-8434-880X
Additional Information:We would like to thank the anonymous referee for careful reading and constructive comments that help improve the clarity of this paper. This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program JWST-ERS-1324. We acknowledge financial support from NASA through grant JWST-ERS-1324. X.W. is supported by CAS Project for Young Scientists in Basic Research, Grant No. YSBR-062. X.W. thanks Zach Hemler for kindly providing his compilations of gradient measurements from the literature and Patricia Tissera for providing the tabulated results of the latest EAGLE simulations. K.G. acknowledges support from Australian Research Council Laureate Fellowship FL180100060. M.B. acknowledges support from the Slovenian national research agency ARRS through grant N1-0238.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
NASANAS 5-03127
Chinese Academy of SciencesYSBR-062
Australian Research CouncilFL180100060
Issue or Number:2
Record Number:CaltechAUTHORS:20221031-575177800.23
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:117661
Deposited By: Research Services Depository
Deposited On:09 Nov 2022 20:01
Last Modified:11 Nov 2022 18:32

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