Metallicity Gradients in Modern Cosmological Simulations. I. Tension between Smooth Stellar Feedback Models and Observations

Alex M. Garcia; Paul Torrey; Aniket Bhagwat; Ruby J. Wright; Qian-Hui Chen; Kathryn Grasha; Sophia Ridolfo; Z. S. Hemler; Arnab Sarkar; Priyanka Chakraborty; Erica J. Nelson; Ryan L. Sanders; Tiago Costa; Mark Vogelsberger; Lisa J. Kewley; Sara L. Ellison; Lars Hernquist

doi:10.3847/1538-4357/adea51

The Astrophysical Journal (Jan 2025)

Metallicity Gradients in Modern Cosmological Simulations. I. Tension between Smooth Stellar Feedback Models and Observations

Alex M. Garcia,
Paul Torrey,
Aniket Bhagwat,
Ruby J. Wright,
Qian-Hui Chen,
Kathryn Grasha,
Sophia Ridolfo,
Z. S. Hemler,
Arnab Sarkar,
Priyanka Chakraborty,
Erica J. Nelson,
Ryan L. Sanders,
Tiago Costa,
Mark Vogelsberger,
Lisa J. Kewley,
Sara L. Ellison,
Lars Hernquist

Affiliations

Alex M. Garcia: ORCiD; Department of Astronomy, University of Virginia , 530 McCormick Road, Charlottesville, VA 22904, USA ; [email protected]; Virginia Institute for Theoretical Astronomy, University of Virginia , Charlottesville, VA 22904, USA; The NSF-Simons AI Institute for Cosmic Origins , USA
Paul Torrey: ORCiD; Department of Astronomy, University of Virginia , 530 McCormick Road, Charlottesville, VA 22904, USA ; [email protected]; Virginia Institute for Theoretical Astronomy, University of Virginia , Charlottesville, VA 22904, USA; The NSF-Simons AI Institute for Cosmic Origins , USA
Aniket Bhagwat: ORCiD; Max Planck Institut für Astrophysik , Karl Schwarzschild Straße 1, D-85741 Garching, Germany
Ruby J. Wright: ORCiD; International Centre for Radio Astronomy Research (ICRAR), M468, University of Western Australia , 35 Stirling Highway, Crawley, WA 6009, Australia
Qian-Hui Chen: ORCiD; Research School of Astronomy & Astrophysics, Australian National University , Canberra 2611, Australia; ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) , Australia
Kathryn Grasha: ORCiD; Research School of Astronomy & Astrophysics, Australian National University , Canberra 2611, Australia; ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) , Australia; Visiting Fellow, Harvard-Smithsonian Center for Astrophysics , 60 Garden Street, Cambridge, MA 02138, USA
Sophia Ridolfo: ORCiD; ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) , Australia; Harvard-Smithsonian Center for Astrophysics , 60 Garden Street, Cambridge, MA 02138, USA
Z. S. Hemler: ORCiD; Department of Astrophysical Sciences, Princeton University , Peyton Hall, Princeton, NJ 08544, USA
Arnab Sarkar: ORCiD; Kavli Institute for Astrophysics and Space Research , Massachusetts Institute of Technology, 70 Vassar Street, Cambridge, MA 02139, USA
Priyanka Chakraborty: ORCiD; Harvard-Smithsonian Center for Astrophysics , 60 Garden Street, Cambridge, MA 02138, USA
Erica J. Nelson: ORCiD; Department for Astrophysical and Planetary Science, University of Colorado , Boulder, CO 80309, USA
Ryan L. Sanders: ORCiD; Department of Physics and Astronomy, University of Kentucky , 505 Rose Street, Lexington, KY 40506, USA
Tiago Costa: ORCiD; School of Mathematics, Statistics and Physics, Newcastle University , Newcastle upon Tyne NE1 7RU, UK
Mark Vogelsberger: ORCiD; Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology , Cambridge, MA 02139, USA
Lisa J. Kewley: ORCiD; Harvard-Smithsonian Center for Astrophysics , 60 Garden Street, Cambridge, MA 02138, USA
Sara L. Ellison: ORCiD; Department of Physics & Astronomy, University of Victoria , Finnerty Road, Victoria, BC V8P 1A1, Canada
Lars Hernquist: ORCiD; Harvard-Smithsonian Center for Astrophysics , 60 Garden Street, Cambridge, MA 02138, USA

DOI: https://doi.org/10.3847/1538-4357/adea51
Journal volume & issue: Vol. 989, no. 2
p. 147

Abstract

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The metallicity of galaxies, and its variation with galactocentric radius, provides key insights into the formation histories of galaxies and the physical processes driving their evolution. In this work, we analyze the radial metallicity gradients of star-forming galaxies in the EAGLE, Illustris, IllustrisTNG, and SIMBA cosmological simulations across broad mass (10 ^8.0 M _⊙ ≤ M _⋆ ≲ 10 ^12.0 M _⊙ ) and redshift (0 ≤ z ≤ 8) ranges. We find that all simulations predict strong negative (i.e., radially decreasing) metallicity gradients at early cosmic times, likely due to their similar treatments of relatively smooth stellar feedback not providing sufficient mixing to quickly flatten gradients. The strongest redshift evolution occurs in galaxies with stellar masses of 10 ^10.0 –10 ^11.0 M _⊙ , while galaxies with stellar mass 10 ^11 M _⊙ exhibit weaker redshift evolution. Our result of negative gradients at high redshift contrast with the many positive and flat gradients in the 1 6, the negative gradients observed with JWST and the Atacama Large Millimeter/submillimeter Array are flatter than those in simulations, albeit with closer agreement than at lower redshift. Overall, we suggest that these smooth stellar feedback galaxy simulations may not sufficiently mix their metal content radially, and that either stronger stellar feedback or additional subgrid turbulent metal diffusion models may be required to better reproduce observed metallicity gradients.

Published in The Astrophysical Journal

ISSN: 1538-4357 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Astronomy: Astrophysics
Website: https://iopscience.iop.org/journal/0004-637X

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