DESI Strong Lens Foundry V: A Sample of HST-Observed Strong Lenses Modeled with GIGA-Lens
Xiaosheng Huang, David Alvarez-Garcia, Monica Ubeda, Vikram Bhamre, Sean Xu, S. Baltasar, N. Ratier-Werbin, F. Urcelay, S. Agarwal, A. Cikota, Y. Hsu, E. Lin, D. J. Schlegel, E. Silver, C. J. Storfer, M. Tamargo-Arizmendi
TL;DR
This paper presents six galaxy-scale strong lenses identified in DESI and observed with the Hubble Space Telescope, modeled with the GIGA-Lens forward-modeling framework. The key advance is full forward modeling—simultaneous sampling of all lens and source parameters—coupled with convergence validation to ensure robust inferences for complex lens systems. The study demonstrates successful, robust modeling of six HST- SNAP lenses (plus a prior system) with high-quality posterior convergence, enabling precise constraints on mass-density profiles and subhalo populations. The results establish a scalable pathway for applying similar, convergence-validated modeling to larger, high-resolution lens samples from future facilities such as Euclid, JWST, and Roman, with implications for cosmology and tests of dark matter.
Abstract
We present six galaxy-scale strong lenses with HST imaging modeled using GIGA-Lens. This is Paper V of the DESI Strong Lens Foundry series. These systems were discovered in the DESI Legacy Imaging Surveys using ML/AI methods and confirmed with DESI, Keck/NIRES, and VLT/MUSE spectroscopy. They span $z_d = 0.39 - 1.1$ and $z_s = 1.4 - 3.3$. This is the first HST strong lens sample modeled with full forward modeling -- all lens and source parameters sampled simultaneously in a single inference -- with explicit convergence validation using both $\widehat{R}$ and effective sample size (ESS) for each system. All inferred parameters satisfy $\widehat{R} < 1.1$ and ${\rm ESS} \gtrsim 10,000$, demonstrating that GIGA-Lens achieves statistically robust inference even for some of the most complex galaxy-scale lenses known. These results pave the way for scaling to much larger, high-resolution strong lens samples from HST, Euclid, JWST, and Roman. Convergence-validated modeling will be critical for key science goals, including constraining the mass-density profile of galaxies, detecting low-mass dark matter (sub)halos, and delivering precise and accurate cosmological constraints.