Princeton University Dark Cosmos Seminar

Abstract: Self-interacting dark matter (SIDM) is a well-motivated extension of ΛCDM that can alter the inner structure of haloes via collisional heat transport. It has been explored as a possible solution to small-scale tensions such as the cusp--core problem. SIDM can also produce dense dark substructures through gravothermal core collapse, potentially observable via perturbations to cold stellar streams or through strong gravitational lensing. In this talk, I present a new Monte-Carlo-based SIDM module for the moving-mesh code AREPO-2. The implementation uses (i) a dedicated neighbour-search tree for dark-matter particles and (ii) a new hypercube-based communication scheme that naturally supports multiple scattering events per particle within a single timestep. Together, these improvements yield a substantial speed-up compared to legacy SIDM implementations and bring the runtime close to that of pure CDM simulations. Finally, the module is designed to be easily extended to arbitrary two-body dark-matter interactions, without requiring detailed knowledge of the underlying parallelisation scheme, enabled by a simplified programming interface.