Metallicity Gradients in Modern Cosmological Simulations II: The Role of Bursty Versus Smooth Feedback at High-Redshift

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

arXiv · 2510.26877

Metallicity Gradients in Modern Cosmological Simulations II: The Role of Bursty Versus Smooth Feedback at High-Redshift

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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 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 $3 10^{9}~{\rm M_\odot}$. 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 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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Alex M. Garcia, Paul Torrey, Aniket Bhagwat, Xuejian Shen, Mark Vogelsberger, William McClymont, Jaya Nagarajan-Swenson, Sophia G. Ridolfo, Peixin Zhu, Dhruv T. Zimmerman, Oliver Zier, Sarah Biddle, Arnab Sarkar, Priyanka Chakraborty, Ruby J. Wright, Kathryn Grasha, Tiago Costa, Laura Keating, Rahul Kannan, Aaron Smith, Enrico Garaldi, Ewald Puchwein, Benedetta Ciardi, Lars Hernquist, Lisa J. Kewley. 2025-10-30. Metallicity Gradients in Modern Cosmological Simulations II: The Role of Bursty Versus Smooth Feedback at High-Redshift. https://arxiv.org/abs/2510.26877

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