# Survival of the most compact: the life and death of satellite halos in self-interacting dark matter

**Authors:** David Klemmer, Moritz S. Fischer, Kimberly K. Boddy, Manoj Kaplinghat, Laura Sagunski  
**arXiv:** [2603.19362](https://arxiv.org/abs/2603.19362)  
**Date:** 2026-03-19  
**Summary page:** https://www.summarizepaper.com/en/paper/2603.19362v1/

## Key points

- Self-interacting dark matter (SIDM) models are important for explaining galactic rotation curves and gravitational lensing signatures
- SIDM models are crucial for studying satellite galaxies and dark subhalos
- A simulation framework using N-body simulations was developed to explore the evolution of subhalos in SIDM scenarios
- The Eddington inversion method was used to accurately model the local velocity distribution within the halo
- Environmental factors, particularly scattering-induced subhalo-halo interactions, significantly impact subhalo evolution over time
- SIDM subhalos exhibit a wider range of central densities and density profile slopes compared to collisionless dark matter scenarios
- Accurately modeling scattering-induced subhalo-halo interactions is important for predicting SIDM subhalo density profiles

## Summary

Self-interacting dark matter (SIDM) models have gained significant attention for their potential to explain the diversity in galactic rotation curves and unique gravitational lensing signatures. These models are particularly important for studying satellite galaxies and dark subhalos, which serve as crucial testing grounds. To further explore the evolution of subhalos in SIDM scenarios with velocity- and angle-dependent self-interacting cross sections, a simulation framework was developed using N-body simulations. The host halo was treated analytically, while the scattering-induced subhalo-halo interaction process was modeled using virtual host particles. One key innovation of this work was the use of the Eddington inversion method to accurately model the local velocity distribution within the halo. By incorporating tidal stripping and tidal heating effects, this simulation framework provided a cost-efficient way to study SIDM subhalos in realistic environments. The study tested both isotropic and forward-dominated self-scattering cases, representing extremes in angular dependence of the self-interaction cross section. The results revealed that environmental factors, particularly scattering-induced subhalo-halo interactions, had a significant impact on subhalo evolution over time, leading to complex structural changes. Compared to collisionless dark matter scenarios, SIDM subhalos exhibited a wider range of central densities and density profile slopes. This enhanced diversity in mass profiles could leave observable imprints on strong lensing systems and satellite galaxies. Overall, this study emphasized the importance of accurately modeling scattering-induced subhalo-halo interactions for predicting SIDM subhalo density profiles. The findings underscored how SIDM models can lead to a richer variety of structural outcomes at both galactic and sub-galactic scales compared to traditional collisionless dark matter models.