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Peer-reviewedCC BYThe Astrophysical Journal

Galaxy Size and Rotation Curve Diversity in ΛCDM with Baryons

  • Akaxia Cruz1,2
  • Alyson M. Brooks1,3
  • Mariangela Lisanti1,2
  • Annika H. G. Peter4,5
  • Robel Geda2
  • Thomas Quinn6
  • Michael Tremmel7
  • Ferah Munshi8
  • Ben Keller9
  • James W. Wadsley10
10 affiliations
  1. 1Flatiron Institute
  2. 2Princeton University
  3. 3The State University of New Jersey
  4. 4Ohio State University
  5. 5The Ohio State University
  6. 6University of Washington
  7. 7University College Cork
  8. 8George Mason University
  9. 9The University of Memphis
  10. 10McMaster University
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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 M 200 ∼ 10 10 –10 11 M ⊙ and M * ∼ 10 7 –10 9 M ⊙ , designed to target the mass range where the galaxy rotation curve diversity is maximized, i.e., between V max ∼ 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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Cite

BibTeXRIS
BibTeX
@article{cruz2026galaxy,
  title = {{Galaxy Size and Rotation Curve Diversity in ΛCDM with Baryons}},
  author = {Akaxia Cruz and Alyson M. Brooks and Mariangela Lisanti and Annika H. G. Peter and Robel Geda and Thomas Quinn and Michael Tremmel and Ferah Munshi and Ben Keller and James W. Wadsley},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = jul,
  doi = {10.3847/1538-4357/ae69ce},
  url = {https://doi.org/10.3847/1538-4357/ae69ce},
  note = {CC BY},
}
RIS
TY  - JOUR
TI  - Galaxy Size and Rotation Curve Diversity in ΛCDM with Baryons
AU  - Akaxia Cruz
AU  - Alyson M. Brooks
AU  - Mariangela Lisanti
AU  - Annika H. G. Peter
AU  - Robel Geda
AU  - Thomas Quinn
AU  - Michael Tremmel
AU  - Ferah Munshi
AU  - Ben Keller
AU  - James W. Wadsley
PY  - 2026
DA  - 2026/07/02
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/ae69ce
UR  - https://doi.org/10.3847/1538-4357/ae69ce
AB  - 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 M 200 ∼ 10 10 –10 11 M ⊙ and M * ∼ 10 7 –10 9 M ⊙ , designed to target the mass range where the galaxy rotation curve diversity is maximized, i.e., between V max ∼ 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.
SN  - 0004-637X
SN  - 1538-4357
ER  -