JWST's TEMPLATES for Star Formation: The First Resolved Gas-phase Metallicity Maps of Dust-obscured Star-forming Galaxies at z ∼ 4

Abstract

We present the first spatially resolved maps of gas-phase metallicity for two dust-obscured star-forming galaxies at z ∼ 4, from the JWST TEMPLATES Early Release Science program, derived from NIRSpec integral field unit spectroscopy of the Hα and [N ii] emission lines. Empirical optical line calibrations are used to determine that the sources are globally enriched to near-solar levels. While one source shows elevated [N ii]/Hα ratios and broad Hα emission consistent with the presence of an active galactic nucleus in a ≳1 kpc region, we argue that both systems have already undergone significant metal enrichment as a result of their extremely high star formation rates. Utilizing Atacama Large Millimeter/submillimeter Array rest-frame 380 μm continuum and [Ci](3P2–3P1) line maps we compare the spatial variation of the metallicity and gas-to-dust ratio in the two galaxies, finding the two properties to be anticorrelated on highly resolved spatial scales, consistent with various literature studies of z ∼ 0 galaxies. The data are indicative of the enormous potential of JWST to probe the enrichment of the interstellar medium on ∼kpc scales in extremely dust-obscured systems at z ∼ 4 and beyond.

An ALMA Spectroscopic Survey of the Brightest Submillimeter Galaxies in the SCUBA-2-COSMOS Field (AS2COSPEC): Physical Properties of z = 2–5 Ultra- and Hyperluminous Infrared Galaxies

“…Our MBB-based median values are also consistent with the estimates of the ALESS and AS2UDS SMGs when the restframe 870 μm luminosity is used as a tracer of M dust (Birkin et al 2021). The relatively low gas-to-dust ratio could suggest supersolar gas-phase metallicity, which is in line with SMGs being heavily dust-enriched and consistent with some recent results (Birkin et al 2023;Eales et al 2023;Peng et al 2023).…”

TEMPLATES: Characterization of a Merger in the Dusty Lensing SPT0418–47 System

“…Originally discovered as a submillimeter source by the South Pole Telescope (SPT; Vieira et al 2013), SPT0418−47 is known to have a high SFR (∼280 M e yr −1 ) with a dense, solarmetallicity interstellar medium, from observations with the Atacama Pathfinder EXperiment and ALMA (De Breuck et al 2019) and from JWST spectroscopy (Birkin et al 2023). Spilker et al (2020) also observed an outflow of molecular gas in this galaxy with M 150 out  ~Me yr −1 .…”

“…For both codes, we use a flexible attenuation curve parameterization that allows for a variable UV-optical slope and V-band attenuation: specifically, CIGALE uses the parameterization from Boquien et al (2019) and PROSPECTOR that of Kriek & Conroy (2013). The metallicity is allowed to vary for SPT0418A, and we apply a uniform prior on the metallicity between 80% and 125% of solar, consistent with De Breuck et al (2019; 0.3 < Z/Z e < 1.3), and based on our teamʼs spectroscopic analysis (Birkin et al 2023).…”

“…For SPT0418B, we set a uniform prior between 65% and 75% solar on the metallicity for PROSPECTOR, based upon the NIRSpec analysis of Birkin et al (2023). We fix the metallicity to solar for CIGALE, as this is the closest metallicity value available in the code.…”

TEMPLATES: A Robust Outlier Rejection Method for JWST/NIRSpec Integral Field Spectroscopy

“…We developed this algorithm in the TEMPLATES ERS collaboration to replace the outlier rejection step for the reasons outlined above (e.g., Birkin et al 2023). We continue to use this algorithm in tandem with the current outlier rejection step in the pipeline to achieve the cleanest data products possible (see Section 3 for the motivation for this combined choice, for jwst pipeline versions 1.11.3 and later).…”