A Universal Analytic Model for Gravitational Lensing by Self-Interacting Dark Matter Halos

TL;DR

This paper introduces an analytical model for gravitational lensing by self-interacting dark matter halos, improving understanding of their lensing features during various evolutionary phases and including baryonic effects.

Contribution

It provides a refined, parametric analytical model for SIDM halo lensing, especially in the core-collapse regime, building on previous approaches and incorporating baryonic influences.

Findings

Accurately models deflection angles and surface density profiles.

Analyzes lensing features like critical curves and caustics during halo evolution.

Provides publicly available implementation for further research.

Abstract

We present a model for analytically calculating gravitational lensing by self-interacting dark matter (SIDM) halos. Leveraging the universal behavior of SIDM halos during gravothermal evolution, we calibrate the lensing potential using a fluid simulation, normalizing the evolution time to align with established scenarios. From this potential, we derive explicit equations for the deflection angle and surface density profile, quantifying their deviations from numerical results. Our model builds on the parametric approach of arXiv:2305.16176, providing refinements in the deep core-collapse regime and enabling more comprehensive lensing studies. We explore characteristic lensing features, including critical curves and caustics, for SIDM halos in isolation and within a main halo, tracking their evolution through the gravothermal phase. We also examine signatures in the self-similar regime of core collapsed halos and highlight the role of baryonic effects in realistic halos. The application of our model extends to generic halos, whose profiles fit one or a superposition of our parametric forms. We make our implementation publicly available on https://github.com/HouSiyuan2001/SIDM_Lensing_Model to support further research.