Self-interacting dark matter in the center of a Local Group dwarf galaxy and its satellites
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| Main Authors: | , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866911195245576192 |
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| author | Gutcke, Thales A. Despali, Giulia O'Neil, Stephanie Vogelsberger, Mark Fattahi, Azadeh Sanders, David B. |
| author_facet | Gutcke, Thales A. Despali, Giulia O'Neil, Stephanie Vogelsberger, Mark Fattahi, Azadeh Sanders, David B. |
| contents | We present a detailed comparison of a Local Group dwarf galaxy analogue evolved in two cosmological models: the standard $Λ$CDM and a self-interacting dark matter (SIDM) model with a velocity-dependent cross-section. Both simulations are run with the high-resolution, hydrodynamical LYRA galaxy formation model, allowing us to explore the global and substructure properties of the dwarf in a consistent context. While the overall halo growth, final mass, and subhalo mass functions remain largely unchanged across models, SIDM produces a central dark matter core extending to $\sim$1 kpc, which does not significantly vary with the inclusion of baryons. Baryonic properties, however, differ notably. The SIDM model leads to a 25% reduction in stellar mass and retains more gas within the stellar half-mass radius due to a prolonged quiescent phase in star formation. The stellar distribution is less centrally concentrated, and a population of in-situ star clusters form at late times. Substructure analysis reveals fewer luminous satellites and more stellar-only systems in SIDM, driven in part by tidal stripping that affects the dark matter more than the stars. A subset of satellites undergoes tidal-triggered core collapse after infall, enhancing the diversity of SIDM satellite rotation curves. These differences offer potential observational signatures of SIDM in low-mass galaxies. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_05258 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Self-interacting dark matter in the center of a Local Group dwarf galaxy and its satellites Gutcke, Thales A. Despali, Giulia O'Neil, Stephanie Vogelsberger, Mark Fattahi, Azadeh Sanders, David B. Astrophysics of Galaxies We present a detailed comparison of a Local Group dwarf galaxy analogue evolved in two cosmological models: the standard $Λ$CDM and a self-interacting dark matter (SIDM) model with a velocity-dependent cross-section. Both simulations are run with the high-resolution, hydrodynamical LYRA galaxy formation model, allowing us to explore the global and substructure properties of the dwarf in a consistent context. While the overall halo growth, final mass, and subhalo mass functions remain largely unchanged across models, SIDM produces a central dark matter core extending to $\sim$1 kpc, which does not significantly vary with the inclusion of baryons. Baryonic properties, however, differ notably. The SIDM model leads to a 25% reduction in stellar mass and retains more gas within the stellar half-mass radius due to a prolonged quiescent phase in star formation. The stellar distribution is less centrally concentrated, and a population of in-situ star clusters form at late times. Substructure analysis reveals fewer luminous satellites and more stellar-only systems in SIDM, driven in part by tidal stripping that affects the dark matter more than the stars. A subset of satellites undergoes tidal-triggered core collapse after infall, enhancing the diversity of SIDM satellite rotation curves. These differences offer potential observational signatures of SIDM in low-mass galaxies. |
| title | Self-interacting dark matter in the center of a Local Group dwarf galaxy and its satellites |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2510.05258 |