Speaker
Description
We present an analytic model for gravitational lensing by self-interacting dark matter (SIDM) halos that captures the full range of gravothermal evolution, including the core-collapse regime. Leveraging the universal behavior of SIDM halos, we calibrate the lensing potential using fluid simulations and derive closed-form expressions for the deflection angle and surface density profile. Our model improves upon existing parametric approaches by enabling accurate treatment of the steep inner density profiles that emerge during the late stages of evolution. We apply this framework to study characteristic lensing features such as critical curves and caustics, both for isolated halos and for subhalos embedded within a host. In particular, we examine how the evolution of core-collapsed subhalos modifies lensing observables. We release our method as a public tool on GitHub (https://github.com/HouSiyuan2001/SIDM_Lensing_Model), which is applicable to halos of any mass that can be described by our parametric density profiles. The tool is especially useful for modeling low-mass subhalos, whose collapse can lead to distinctive strong lensing signatures in SIDM scenarios.
