The study of gas-phase metallicity and its spatial distribution at high redshift is crucial to understand the processes that shaped the growth and evolution of galaxies in the early Universe. Here we study the spatially resolved metallicity in three systems at z ∼ 6−8, namely A2744-YD4, BDF-3299, and COSMOS24108, with JWST NIRSpec IFU low-resolution (R ∼ 100) spectroscopic observations. These are among the highest-z sources in which metallicity gradients have been probed so far. Each of these systems hosts several spatial components in the process of merging within a few kiloparsecs, identified from the rest-frame UV and optical stellar continuum and ionised gas emission line maps. The sources have heterogeneous properties, with stellar masses log(M∗/M) ∼7.6–9.3, star formation rates (SFRs) ∼1–15 M yr−1, and gas-phase metallicities 12+log(O/H) ∼7.7–8.3, which exhibit a large scatter within each system. Their properties are generally consistent with those of the highest-redshift samples to date (z ∼ 3−10), though the sources in A2744-YD4 and COSMOS24108 are at the high end of the mass-metallicity relation (MZR) defined by the z ∼ 3−10 sources. Moreover, the targets in this work follow the predicted slope of the MZR at z ∼ 6−8 from most cosmological simulations. The gas-phase metallicity gradients are consistent with being flat in the main sources of each system. Flat metallicity gradients are thought to arise from gas mixing processes on galaxy scales, such as mergers or galactic outflows and supernova winds driven by intense stellar feedback, which wash out any gradient formed in the galaxy. The existence of flat gradients at z ∼ 6 − 8 sets also important constraints on future cosmological simulations and chemical evolution models, whose predictions on the cosmic evolution of metallicity gradients often differ significantly, especially at high redshift, but are mostly limited to z . 3 so far

Gas-phase metallicity gradients in galaxies at z ∼ 6–8

G. Venturi
;
S. Carniani;E. Parlanti;M. Kohandel;A. Pallottini;L. Vallini;A. Ferrara;S. Gallerani;E. Ntormousi;
2024

Abstract

The study of gas-phase metallicity and its spatial distribution at high redshift is crucial to understand the processes that shaped the growth and evolution of galaxies in the early Universe. Here we study the spatially resolved metallicity in three systems at z ∼ 6−8, namely A2744-YD4, BDF-3299, and COSMOS24108, with JWST NIRSpec IFU low-resolution (R ∼ 100) spectroscopic observations. These are among the highest-z sources in which metallicity gradients have been probed so far. Each of these systems hosts several spatial components in the process of merging within a few kiloparsecs, identified from the rest-frame UV and optical stellar continuum and ionised gas emission line maps. The sources have heterogeneous properties, with stellar masses log(M∗/M ) ∼7.6–9.3, star formation rates (SFRs) ∼1–15 M yr−1, and gas-phase metallicities 12+log(O/H) ∼7.7–8.3, which exhibit a large scatter within each system. Their properties are generally consistent with those of the highest-redshift samples to date (z ∼ 3−10), though the sources in A2744-YD4 and COSMOS24108 are at the high end of the mass-metallicity relation (MZR) defined by the z ∼ 3−10 sources. Moreover, the targets in this work follow the predicted slope of the MZR at z ∼ 6−8 from most cosmological simulations. The gas-phase metallicity gradients are consistent with being flat in the main sources of each system. Flat metallicity gradients are thought to arise from gas mixing processes on galaxy scales, such as mergers or galactic outflows and supernova winds driven by intense stellar feedback, which wash out any gradient formed in the galaxy. The existence of flat gradients at z ∼ 6 − 8 sets also important constraints on future cosmological simulations and chemical evolution models, whose predictions on the cosmic evolution of metallicity gradients often differ significantly, especially at high redshift, but are mostly limited to z . 3 so far
2024
Settore FIS/05 - Astronomia e Astrofisica
Settore PHYS-05/A - Astrofisica, cosmologia e scienza dello spazio
Galaxies: abundances; Galaxies: evolution; Galaxies: high-redshift; Galaxies: ISM; Techniques: high angular resolution; Techniques: imaging spectroscopy;
   Winds in galaxies.
   WINGS
   European Commission
   Grant Agreement n. 101040227

   Finding the most distant galaxies with NIRSpec guaranteed time on the James Webb Space Telescope
   FirstGalaxies
   European Commission
   Horizon 2020 Framework Programme
   789056

   The Interstellar Medium of High Redshift Galaxies (INTERSTELLAR)
   INTERSTELLAR
   European Commission
   H2020
   740120
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/148264
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