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Lookup NU author(s): Dr Tiago CostaORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. The distribution of gas-phase metals within galaxies encodes the impact of stellar feedback on galactic evolution. At high redshift, when galaxies are rapidly assembling, feedback-driven outflows and turbulence can strongly reshape radial metallicity gradients. In this work, we use the FIRE-2, SPICE, Thesan Box, and Thesan Zoom cosmological simulations—spanning a range of stellar feedback, from bursty (time-variable) to smooth (steady)—to investigate how these feedback modes shape gas-phase metallicity gradients at 3 < z ≲ 11. Across all models, we find that galaxies with bursty feedback (FIRE-2, SPICE Bursty, and Thesan Zoom) develop systematically flatter (by factors of ∼2–10) metallicity gradients than those with smooth feedback (SPICE Smooth and Thesan Box), particularly at stellar masses M⋆ > 109 M⊙. These results demonstrate that bursty stellar feedback provides sufficient turbulence to prevent strong negative gradients from forming, while smooth stellar feedback does not generically allow for the efficient radial redistribution of metals, thereby keeping gradients steep. Finally, we compare with recent observations, finding that the majority—but, notably, not all—of the observed gradients may favor a bursty stellar feedback scenario. In all, these results highlight the utility of high-resolution observations of gas-phase metallicity at high redshift as a key discriminator of these qualitatively different feedback types.
Author(s): Garcia AM, Torrey P, Bhagwat A, Shen X, Vogelsberger M, McClymont W, Nagarajan-Swenson J, Ridolfo SG, Zhu P, Zimmerman DT, Zier O, Biddle S, Sarkar A, Chakraborty P, Wright RJ, Grasha K, Costa T, Keating L, Kannan R, Smith A, Garaldi E, Puchwein E, Ciardi B, Hernquist L, Kewley LJ
Publication type: Article
Publication status: Published
Journal: Astrophysical Journal
Year: 2026
Volume: 1001
Issue: 2
Print publication date: 20/04/2026
Online publication date: 16/04/2026
Acceptance date: 19/03/2026
Date deposited: 12/05/2026
ISSN (print): 0004-637X
ISSN (electronic): 1538-4357
Publisher: American Astronomical Society
URL: https://doi.org/10.3847/1538-4357/ae561e
DOI: 10.3847/1538-4357/ae561e
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