Galaxy size and rotation curve diversity in ΛCDM with baryons
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Date
10/07/2026
Authors
Cruz, Akaxia
Brooks, Alyson M.
Lisanti, Mariangela
Peter, Annika H.G.
Geda, Robel
Quinn, Thomas
Tremmel, Michael
Munshi, Ferah
Keller, Ben
Wadsley, James
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Abstract
The observed rotation curves of dwarf galaxies exhibit significant diversity at fixed halo mass, challenging galaxy formation within the cold dark matter (CDM) model. Previous cosmological galaxy formation simulations with baryonic physics fail to reproduce the full diversity of rotation curves, suggesting that there is a flaw in baryonic feedback models, observational bias, or that an alternative to CDM must be invoked. In this work, we use the Marvelous Massive Dwarf zoom-in simulations, a suite of high-resolution dwarf simulations with M200 ∼ 1010–1011 M⊙and M* ∼ 107–109 M⊙, designed to target the mass range where the galaxy rotation curve diversity is maximized, i.e., between (Formula presented) Vmax∼70 and 100 km s−1. We add to this a set of low-mass galaxies from the Marvel Dwarf Zoom Volumes to extend the galaxy mass range to lower values. Our fiducial star formation and feedback models produce simulated dwarfs with a broader range of rotation curve shapes, similar to observations. These simulations both create dark matter cores via baryonic feedback, reproducing the slower-rising rotation curves, while also allowing for compact galaxies and steeply rising rotation curves. Our simulated dwarfs also reproduce the observed size–M* relation, including scatter, producing both extended and compact dwarfs for the first time in simulated field dwarfs. However, the slowly rising and high baryon mass fraction, as well as the steeply rising and low baryon mass fraction, remain missing. We explore star formation and feedback models and conclude that previous simulations may have had feedback that was too strong to produce compact dwarfs.
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© 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the https://creativecommons.org/licenses/by/4.0/. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Keywords
Cold dark matter (265) , Dark matter density (354) , Dwarf galaxies (416) , Galaxy formation (595) , Hydrodynamical simulations (767) , Stellar feedback (1602) , [Physics] , Astronomy and Astrophysics , Space and Planetary Science
Citation
Cruz, A, Brooks, A M, Lisanti, M, Peter, A H G, Geda, R, Quinn, T, Tremmel, M, Munshi, F, Keller, B & Wadsley, J 2026, 'Galaxy size and rotation curve diversity in ΛCDM with baryons', Astrophysical Journal, vol. 1005, no. 2, 157, pp. 1-24. https://doi.org/10.3847/1538-4357/ae69ce
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