New Simulations Show Self-Interacting Dark Matter Can Explain Dwarf Galaxy Structures
Researchers present a new dark matter-only cosmological simulation using velocity-dependent self-interacting dark matter (SIDM) and find it can reproduce observed density profiles in dwarf galaxies without requiring baryonic physics. The simulation, part of the MARVEL suite, identifies nine halos undergoing core-collapse gravothermal evolution and benchmarks collapse timescales against an existing parametric model. The findings suggest that the slope of the inner dark matter density profile is a more reliable diagnostic of core-collapse versus core-forming halos than central density amplitude alone.
A new study posted to arXiv introduces a dark matter-only (DMO) cosmological simulation using velocity-dependent self-interacting dark matter (SIDM) with a peak cross section of 50 cm²/g at 35 km/s, part of the MARVEL simulation suite. The authors compare results to the Storm CDM simulation suite, which includes both DMO and hydrodynamics runs with stellar feedback, to test how well SIDM reproduces observed dwarf galaxy density profiles without invoking baryonic processes. The MARVEL SIDM DMO simulation successfully matches core slopes seen in isolated dwarf galaxies and in more massive CDM dwarf halos that include stellar feedback, suggesting SIDM can mimic the effects of baryonic physics in certain regimes. Nine halos with virial masses below 2×10⁹ solar masses are identified as being in the core-collapse phase of gravothermal evolution. Core-collapse timescales derived from the inner density slope agree well with predictions from the Yang et al. (2023) parametric model. Crucially, the inner density slope is found to be less sensitive than central density to both the measurement radius and halo merger history, making it a cleaner observational discriminant. These results have implications for resolving long-standing tensions between cold dark matter predictions and observations of dwarf galaxy interiors.
What's missing
The study is a preprint and has not yet undergone formal peer review. The simulations are dark matter-only and do not self-consistently include baryonic physics in the SIDM runs, so the degree to which stellar feedback might alter the SIDM results remains untested.
What different sources said
- arXiv astro-phCenter
MARVELously Dark: the density profile evolution of dwarf halos in velocity-dependent SIDM
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