Lower central dark matter densities in nearby galaxies than predicted by simulations
Abstract
Baryonic feedback in hydrodynamical simulations is typically invoked to alleviate the core--cusp problem in dwarf galaxies. Yet baryonic processes also induce adiabatic contraction of dark matter, producing overly steep density profiles and excessively high dark matter fractions in the inner regions of massive galaxies. The dark matter distribution of galaxies across a wide stellar-mass range is therefore a critical test for such simulations, but a comprehensive benchmark has remained absent. Here, we consistently measure the dark matter distribution from galaxy centres out to radii of 20--50 kpc for 136 nearby galaxies that together span the local mass--size relation over the stellar mass interval 109--1011.5 M⊙. We identify central regions with lower dark matter densities relative to ΛCDM simulation expectations---whose extent grows from about 10 kpc to >50 kpc as stellar mass increases from 1010 M⊙ to 1011.5 M⊙. Although their physical origin remains unclear, these low--dark matter regions are clearly indicated by the data. Our results provide an important observational benchmark for future hydrodynamical simulations that explore alternative dark matter models and feedback processes.
Related
- MUSE-DARK IV. Comparing Dark Matter Densities to Star Formation Histories in 375 intermediate-z galaxies
- Dark matter haloes from dwarf to massive galaxies: no systematic inner-density tension with ΛCDM hydrodynamical simulations
- The Evolution of Low-ionization Electron Densities in Galaxies across Cosmic Epochs
- Quiescent Galaxies at z > 2 from CAPERS spectroscopy and their Number densities
- Caught Napping by JWST UNCOVER+MegaScience: Constraining bursty star formation histories and number densities of mini-quenched galaxies at redshifts 4-7
BibTeX
@misc{lei2026lower,
title = {{Lower central dark matter densities in nearby galaxies than predicted by simulations}},
author = {Yu Lei and Ling Zhu and Meng Yang and Giulia Despali and Zheng Zheng and Ran Li and Dandan Xu and Niankun Yu and Jesús Falcón-Barroso and Fangzhou Jiang and Glenn van de Ven and Jie Wang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.16740},
eprint = {2609.16740},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.16740},
}
RIS
TY - UNPB
TI - Lower central dark matter densities in nearby galaxies than predicted by simulations
AU - Yu Lei
AU - Ling Zhu
AU - Meng Yang
AU - Giulia Despali
AU - Zheng Zheng
AU - Ran Li
AU - Dandan Xu
AU - Niankun Yu
AU - Jesús Falcón-Barroso
AU - Fangzhou Jiang
AU - Glenn van de Ven
AU - Jie Wang
PY - 2026
DA - 2026/09/15
PB - arXiv
DO - 10.48550/arxiv.2609.16740
UR - https://arxiv.org/abs/2609.16740
AB - Baryonic feedback in hydrodynamical simulations is typically invoked to alleviate the core--cusp problem in dwarf galaxies. Yet baryonic processes also induce adiabatic contraction of dark matter, producing overly steep density profiles and excessively high dark matter fractions in the inner regions of massive galaxies. The dark matter distribution of galaxies across a wide stellar-mass range is therefore a critical test for such simulations, but a comprehensive benchmark has remained absent. Here, we consistently measure the dark matter distribution from galaxy centres out to radii of 20--50 kpc for 136 nearby galaxies that together span the local mass--size relation over the stellar mass interval 10^9--10^11.5 M_⊙. We identify central regions with lower dark matter densities relative to ΛCDM simulation expectations---whose extent grows from about 10 kpc to >50 kpc as stellar mass increases from 10^10 M_⊙ to 10^11.5 M_⊙. Although their physical origin remains unclear, these low--dark matter regions are clearly indicated by the data. Our results provide an important observational benchmark for future hydrodynamical simulations that explore alternative dark matter models and feedback processes.
ER -