The physical origin of positive metallicity radial gradients in high-redshift galaxies: insights from the FIRE-2 cosmological hydrodynamic simulations

Abstract

Using the FIRE-2 cosmological zoom-in simulations, we investigate the temporal evolution of gas-phase metallicity radial gradients of Milky Way-mass progenitors in the redshift range of $0.4<z<3$. We pay special attention to the occurrence of positive (i.e. inverted) metallicity gradients -- where metallicity increases with galactocentric radius. This trend, contrary to the more commonly observed negative radial gradients, has been frequently seen in recent spatially resolved grism observations. The rate of occurrence of positive gradients in FIRE-2 is about $\sim 7\%$ for $0.4<z<3$ and $\sim 13\%$ at higher redshifts ($1.5<z<3$), broadly consistent with observations. Moreover, we investigate the correlations among galaxy metallicity gradient, stellar mass, star formation rate (SFR), and degree of rotational support. Metallicity gradients show a strong correlation with both sSFR and the rotational-to-dispersion velocity ratio ($v_c/\sigma$), implying that starbursts and kinematic morphology of galaxies play significant roles in shaping these gradients. The FIRE-2 simulations indicate that galaxies with high sSFR ($\log (\mathrm{sSFR}[\mathrm{y}{\mathrm{r}}^{-1}])\gtrsim -9.2$) and weak rotational support ($v_c/\sigma \lesssim 1$) are more likely -- by $\sim$15\% -- to develop positive metallicity gradients. This trend is attributed to galaxy-scale gas flows driven by stellar feedback, which effectively redistribute metals within the interstellar medium. Our results support the important role of stellar feedback in governing the chemo-structural evolution and disk formation of Milky Way-mass galaxies at the cosmic noon epoch.

19 pages, 10 figures

References in corpus (27)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• Black Holes on FIRE: Stellar Feedback Limits Early Feeding of Galactic Nuclei
• Metallicity gradients in local field star-forming galaxies: Insights on inflows, outflows, and the coevolution of gas, stars and metals
• Characterizing mass, momentum, energy and metal outflow rates of multi-phase galactic winds in the FIRE-2 cosmological simulations
• FIRE-3: Updated Stellar Evolution Models, Yields, & Microphysics and Fitting Functions for Applications in Galaxy Simulations
• Public data release of the FIRE-2 cosmological zoom-in simulations of galaxy formation
• A relationship between specific star formation rate and metallicity gradient within z=1 galaxies from KMOS-HiZELS
• Gas-phase metallicity gradients of TNG50 star-forming galaxies
• Hot-mode accretion and the physics of thin-disk galaxy formation
• 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
• Rapid disc settling and the transition from bursty to steady star formation in Milky Way-mass galaxies
• 3-D gas-phase elemental abundances across the formation histories of Milky Way-mass galaxies in the FIRE simulations: initial conditions for chemical tagging
• Early results from GLASS-JWST. IV: Spatially resolved metallicity in a low-mass $z\sim 3$ galaxy with NIRISS
• A Relationship Between Stellar Metallicity Gradients and Galaxy Age in Dwarf Galaxies
• The dependence of oxygen and nitrogen abundances on stellar mass from the CALIFA survey
• Gas-phase metallicity gradients in galaxies at $z\sim 6-8$
• Disk settling and dynamical heating: histories of Milky Way-mass stellar disks across cosmic time in the FIRE simulations
• Unusual integrated metallicity profile of our Milky Way
• The evolution of the oxygen abundance gradients in star-forming galaxies in the EAGLE simulations
• The Gas-phase Metallicity Profiles of Star-forming Galaxies in the Modified Accretion Disk Framework
• Spiral Arms are Metal Freeways: Azimuthal Gas-Phase Metallicity Variations in Simulated Cosmological Zoom-in Flocculent Disks
• MSA-3D: Metallicity Gradients in Galaxies at $z\sim 1$ with JWST/NIRSpec Slit-stepping Spectroscopy
• Early results from GLASS-JWST. XXVII. The mass-metallicity relation in lensed field galaxies at cosmic noon with NIRISS
• Environmental dependence of the mass-metallicity relation in cosmological hydrodynamical simulations
• How well do local relations predict gas-phase metallicity gradients? Results from SDSS-IV MaNGA

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• Revisiting the Radial Metallicity Gradient-Age Relation in the Milky Way's Thin and Thick Disks
• KURVS: chemical properties from multiple strong line calibrations for star-forming galaxies at $z\sim 1.5$