Abstract
ABSTRACT Self-interacting dark matter (SIDM) models have the potential to solve the small-scale problems that arise in the cold dark matter paradigm. Simulations are a powerful tool for studying SIDM in the context of astrophysics, but it is numerically challenging to study differential cross-sections that favour small-angle scattering (as in light-mediator models). Here, we present a novel approach to model frequent scattering based on an effective drag force, which we have implemented into the N-body code gadget-3. In a range of test problems, we demonstrate that our implementation accurately models frequent scattering. Our implementation can be used to study differences between SIDM models that predict rare and frequent scattering. We simulate core formation in isolated dark matter haloes, as well as major mergers of galaxy clusters and find that SIDM models with rare and frequent interactions make different predictions. In particular, frequent interactions are able to produce larger offsets between the distribution of galaxies and dark matter in equal-mass mergers.
Highlights
Dark matter (DM) is an essential component of the standard cosmological model (Lambda cold dark matter, ΛCDM), which was introduced to explain a variety of observations, such as the formation of large-scale structure and the cosmic microwave background
We find that the effects for frequent self-interacting dark matter (fSIDM) can be substantially larger than those previously found for rare selfinteracting dark matter (rSIDM)
We find that the maximum core size is nearly independent of the self-interaction cross-section for both rSIDM and fSIDM, in agreement with earlier findings for rare self-interactions (e.g. Kochanek & White 2000)
Summary
Dark matter (DM) is an essential component of the standard cosmological model (Lambda cold dark matter, ΛCDM), which was introduced to explain a variety of observations, such as the formation of large-scale structure and the cosmic microwave background. These observations can be explained remarkably well under the assumption that DM is cold and collisionless (e.g. Planck Collaboration et al 2020). Up to five small-scale problems are considered. Not all of them describe actual problems of ΛCDM and at least the missing satellites can be explained within the cosmological standard model Not all of them describe actual problems of ΛCDM and at least the missing satellites can be explained within the cosmological standard model (e.g. Kim et al 2018)
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