Metallicity Gradients in Modern Cosmological Simulations. II. The Role of Bursty versus Smooth Feedback at High Redshift

Abstract 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 ⋆ > 10 9 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.

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Publication Details

Journal
The Astrophysical Journal
Published
2026-04-16
DOI
https://doi.org/10.3847/1538-4357/ae561e
Citations
2
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
29.43

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article

Metallicity Gradients in Modern Cosmological Simulations. II. The Role of Bursty versus Smooth Feedback at High Redshift

Tiago Costa, Peixin Zhu, Mark Vogelsberger, Sophia G. Ridolfo et al.
2 citations
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
29.43
article

Metallicity Gradients in Modern Cosmological Simulations. II. The Role of Bursty versus Smooth Feedback at High Redshift

Tiago Costa, Peixin Zhu, Mark Vogelsberger, Sophia G. Ridolfo, Oliver Zier, B. Ciardi, Enrico Garaldi, Lisa J. Kewley, Arnab Sarkar, Ruby J. Wright, William McClymont, Kathryn Grasha, Priyanka Chakraborty, Rahul Kannan, Ewald Puchwein, Dhruv T. Zimmerman, Xuejian Shen, Lars Hernquist, Aaron Smith, Paul Torrey, Alex M. Garcia, Aniket Bhagwat, Laura C. Keating, Jaya Nagarajan-Swenson, Sarah Biddle
article en
2 citations

Abstract

Abstract 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 ⋆ > 10 9 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.

The Astrophysical JournalVol. 1001(2)
Australian National University (AU), Vassar College (US), Philipps University of Marburg (DE), The University of Texas at Dallas (US), Kavli Institute for the Physics and Mathematics of the Universe (JP), The University of Western Australia (AU), York University (CA), University of Cambridge (GB), Leibniz Institute for Astrophysics Potsdam (DE), University of Florida (US), Max Planck Institute for Astrophysics (DE), Simons Foundation (US), Center for Astrophysics Harvard & Smithsonian (US), International Centre for Radio Astronomy Research (AU), UK Astronomy Technology Centre (GB), University of Virginia (US), Massachusetts Institute of Technology (US), The University of Tokyo (JP), University of Arkansas at Fayetteville (US), Newcastle University (GB), University of Edinburgh (GB)
National Science Foundation, National Aeronautics and Space Administration, Simons Foundation, Virginia Space Grant Consortium, Massachusetts Institute of Technology, York University, Royal Society, University of Cambridge, Natural Sciences and Engineering Research Council of Canada, Science and Technology Facilities Council
Openalex Percentile: Top 1%
Galaxies: Formation, Evolution, Phenomena
29.43
DOIOpen Access PDFOpenAlex
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