Gas-phase metallicity gradients in galaxies at $z\sim 6-8$

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 $z\sim 6-8$, namely A2744-YD4, BDF-3299, and COSMOS24108, with JWST NIRSpec IFU low-resolution ($R\sim 100$) 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 kpc, 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($M_{\ast }/M_{\odot })\sim 7.6-9.3$, star formation rates (SFRs) $\sim 1-15$ $M_{\odot }$ yr${}^{-1}$, and gas-phase metallicities 12+log(O/H) $\sim 7.7-8.3$, which exhibit a large scatter within each system. Their properties are generally consistent with those of the highest-$z$ samples to date ($z\sim 3-10$), though the sources in A2744-YD4 and COSMOS24108 are at the high end of the mass-metallicity relation (MZR) defined by the $z\sim 3-10$ sources. Moreover, the targets in this work follow the predicted slope of the MZR at $z\sim 6-8$ 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 SN winds driven by intense stellar feedback, which wash out any gradient formed in the galaxy. The existence of flat gradients at $z\sim 6-8$ sets also important constraints on cosmological simulations and chemical evolution models, whose predictions on the cosmic evolution of metallicity gradients differ significantly, but are mostly limited to $z<3$ so far.

15 pages (+5 appendix); 7 figures (+8 in appendix); in production on A&A

References in corpus (41)

• Array Programming with NumPy
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• JADES NIRSpec Spectroscopy of GN-z11: Lyman-$\alpha$ emission and possible enhanced nitrogen abundance in a $z=10.60$ luminous galaxy
• The Mass-Metallicity and the Fundamental Metallicity Relation revisited on a fully Te-based abundance scale for galaxies
• The Main Sequence of star-forming galaxies across cosmic times
• Dust in the reionization era: ALMA observations of a $z$=8.38 Galaxy
• New fully empirical calibrations of strong-line metallicity indicators in star forming galaxies
• The chemical enrichment in the early Universe as probed by JWST via direct metallicity measurements at z~8
• Metallicity gradients in local field star-forming galaxies: Insights on inflows, outflows, and the coevolution of gas, stars and metals
• The evolution of the Galactic metallicity gradient from high-resolution spectroscopy of open clusters
• Observational constraints on the merger history of galaxies since $z\approx 6$: Probabilistic galaxy pair counts in the CANDELS fields
• CHAOS I: Direct Chemical Abundances for HII Regions in NGC 628
• JADES: Probing interstellar medium conditions at $z\sim 5.5-9.5$ with ultra-deep JWST/NIRSpec spectroscopy
• New Constraints on the Faint-end of the UV Luminosity Function at z~7-8 using the Gravitational Lensing of the Hubble Frontier Fields Cluster A2744
• Tracing the reionization epoch with ALMA: [CII] emission in z~7 galaxies
• Deep into the structure of the first galaxies: SERRA views
• Simulating cosmic metal enrichment by the first galaxies
• Zooming on the internal structure of $z\simeq 6$ galaxies
• Early results from GLASS-JWST. XIV: A spectroscopically confirmed protocluster 650 million years after the Big Bang
• The MOSDEF Survey: the Variation of the Dust Attenuation Curve with Metallicity
• Stochastic star formation in early galaxies: JWST implications
• EMPRESS. V. Metallicity Diagnostics of Galaxies over 12+log(O/H)=~6.9-8.9 Established by a Local Galaxy Census: Preparing for JWST Spectroscopy
• The KLEVER Survey: Spatially resolved metallicity maps and gradients in a sample of 1.2 < z < 2.5 lensed galaxies
• A relationship between specific star formation rate and metallicity gradient within z=1 galaxies from KMOS-HiZELS
• JADES: Detecting [OIII]$\lambda 4363$ Emitters and Testing Strong Line Calibrations in the High-$z$ Universe with Ultra-deep JWST/NIRSpec Spectroscopy up to $z\sim 9.5$
• The physics of gas phase metallicity gradients in galaxies
• CLEAR: The Gas-Phase Metallicity Gradients of Star-Forming Galaxies at 0.6 < z < 2.6
• The Grism Lens-Amplified Survey from Space (GLASS) X. Sub-kpc resolution gas-phase metallicity maps at cosmic noon behind the Hubble Frontier Fields cluster MACS1149.6+2223
• The Grism Lens-Amplified Survey from Space (GLASS). II. Gas-phase metallicity and radial gradients in an interacting system at z~2
• The Absence of [CII] 158$\mu$m Emission in Spectroscopically-Confirmed Galaxies at $z>8$
• The GLASS-JWST Early Release Science Program. III. Strong lensing model of Abell 2744 and its infalling regions
• Constraining the PopIII IMF with high-z GRBs
• GA-NIFS: The core of an extremely massive proto-cluster at the Epoch of Reionization probed with JWST/NIRSpec
• Early results from GLASS-JWST. IV: Spatially resolved metallicity in a low-mass $z\sim 3$ galaxy with NIRISS
• The Metallicity and Elemental Abundance Gradients of Simulated Galaxies, and their Environmental Dependence
• The Mass-Metallicity Relation of Dwarf Galaxies at Cosmic Noon from JWST Observations
• Reionization and the ISM/Stellar Origins with JWST and ALMA (RIOJA): The core of the highest redshift galaxy overdensity at $z=7.88$ confirmed by NIRSpec/JWST
• The evolution of the oxygen abundance gradients in star-forming galaxies in the EAGLE simulations
• The radial metallicity gradient and the history of elemental enrichment in M81 through emission-line probes
• First Census of Gas-phase Metallicity Gradients of Star-forming Galaxies in Overdense Environments at Cosmic Noon
• The stellar populations of high-redshift dwarf galaxies

Cited by in corpus (24)

• GA-NIFS: Multi-phase analysis of a star-forming galaxy at $z\sim 5.5$
• Redshift-dependent galaxy formation efficiency at $z=5-13$ in the FirstLight simulations
• Anatomy of a z=6 Lyman-α emitter down to parsec scales: extreme UV slopes, metal-poor regions and possibly leaking star clusters
• GA-NIFS: JWST/NIRSpec IFS view of the z~3.5 galaxy GS5001 and its close environment at the core of a large-scale overdensity
• The dawn of disks: unveiling the turbulent ionised gas kinematics of the galaxy population at $z\sim 4-6$ with JWST/NIRCam grism spectroscopy
• The mass-metallicity relation as a ruler for galaxy evolution: insights from the James Webb Space Telescope
• MSA-3D: Metallicity Gradients in Galaxies at $z\sim 1$ with JWST/NIRSpec Slit-stepping Spectroscopy
• Spatially resolved emission lines in galaxies at $4\le z<10$ from the JADES survey: evidence for enhanced central star formation
• Direct-method metallicity gradients derived from spectral stacking with SDSS-IV MaNGA
• Evolution of the radial ISM metallicity gradient in the Milky Way disk since redshift $\approx 3$
• Detailed Study of Stars and Gas in a z = 8.3 Massive Merger with Extreme Dust Conditions
• Exploring Spatially-Resolved Metallicities, Dynamics and Outflows in Low-Mass Galaxies at $z\sim 7.6$
• Spatially resolved [CII]-gas conversion factor in early galaxies
• Effects of secular growth and mergers on the evolution of metallicity gradients and azimuthal variations in a Milky Way-like galaxy
• The physical origin of positive metallicity radial gradients in high-redshift galaxies: insights from the FIRE-2 cosmological hydrodynamic simulations
• GA-NIFS: Dissecting the multiple sub-structures and probing their complex interactions in the \Lyalpha emitter galaxy CR7 at z = 6.6 with JWST/NIRSpec
• A two-phase model of galaxy formation: III. The formation of globular clusters
• The ALPINE-ALMA [CII] Survey: Modelling ALMA and JWST lines to constrain the interstellar medium of $z\sim 5$ galaxies
• Metal line emission around z<1 galaxies
• Radiation-driven dusty outflows from early galaxies
• JWST reveals a supernova following a gamma-ray burst at z $\simeq$ 7.3
• A theoretical investigation of far-infrared fine structure lines at $z>6$ and of the origin of the [OIII]88/[CII]158 enhancement
• Revisiting the Radial Metallicity Gradient-Age Relation in the Milky Way's Thin and Thick Disks
• The ALPINE-CRISTAL-JWST Survey: Gas-phase abundance gradients of main sequence star-forming galaxies and their kinematics at $4<z<6$