# TDCOSMO. XXVII. JWST-based Lens Models and H$_0$ Measurement of WFI2033, HE0435, and PG1115

**Authors:** D. M. Williams, T. Treu, D. P. Johnson, P. Mozumdar, S. Knabel, S. Birrer, C. D. Fassnacht, A. Galan, A. J. Shajib, K. C. Wong, M. Cappellari, F. Courbin, T. Morishita, V. Motta, D. Sluse, M. Stiavelli  
**arXiv:** [2608.27566](https://arxiv.org/abs/2608.27566)  
**Date:** 2026-08-27  
**Summary page:** https://www.summarizepaper.com/en/paper/2608.27566v1/

## Key points

- Researchers use time-delay cosmography to measure the Hubble-Lemaitre constant (H_0) independently.
- Advanced lens models are presented for three quadruply imaged quasars (WFI2033-4723, HE0435-1223, PG1115+080) using JWST-NIRCam/F115W imaging.
- STARRED modeling technique is employed along with improved external convergence estimates, published time delays, and aperture-integrated stellar velocity dispersions from JWST NIRSpec to infer H_0.
- Analysis was blind for two quasars (HE0435-1223 and PG1115+080) but not blind for WFI2033-4723 due to a previously published model.
- Consistency with previous HST-based work is maintained by limiting the analysis to cases without internal mass-sheet degeneracy ($λ_{\rm int}=1$).
- Within a flat $Λ$CDM framework and assuming a uniform prior on $Ω_{\rm m}$, H_0 values are determined for each quasar: 71.8$_{-7.0}^{+9.2}$ km s$^{-1}$ Mpc$^{-1}$ for PG1115+080, 74.2$_{-4.2}^{+4.2}$ km s$^{-1}$ Mpc$^{-1}$ for HE0435-1223, and 73.4$_{-4.4}^{+3.4}$ km s$^{-1}$ Mpc$^{-1}$ for WFI2033-4723.
- Combining results from all three lenses yields an overall H_0 value of 73.5$_{-2.8}^{+2.7}$ km s$^{-1}$ Mpc$^{-1}, aligning closely with HST-based findings but with reduced variability across systems.
- The newly developed lens models will be integrated into the TDCOSMO-2026 milestone paper using a hierarchical approach with free $λ_{\rm int}.
- Future JWST NIRCam targets will help refine uncertainties towards achieving percent-level precision in determining H_0.

## Summary

The researchers in this study utilize time-delay cosmography to directly and independently measure the Hubble-Lemaitre constant (H_0). They present advanced lens models for three quadruply imaged quasars (WFI2033-4723, HE0435-1223, PG1115+080) based on JWST-NIRCam/F115W imaging. By employing the STARRED modeling technique and combining NIRCam-based lens models with improved external convergence estimates, published time delays, and aperture-integrated stellar velocity dispersions from JWST NIRSpec, they are able to infer H_0. The analysis was conducted blindly for two of the quasars (HE0435-1223 and PG1115+080), while it was not blind for WFI2033-4723 as it builds upon a previously published model. To ensure consistency with previous HST-based work, the analysis is limited to cases without internal mass-sheet degeneracy ($λ_{\rm int}=1$). The researchers evaluate the impact of enhanced imaging techniques, single-aperture kinematics, and environmental measurements on central values and uncertainties. Within a flat $Λ$CDM framework and assuming a uniform prior on $Ω_{\rm m}$, they determine H_0 values of 71.8$_{-7.0}^{+9.2}$ $λ_{\rm int}$ km s$^{-1}$ Mpc$^{-1}$ for PG1115+080, 74.2$_{-4.2}^{+4.2}$ $λ_{\rm int}$ km s$^{-1}$ Mpc$^{-1}$ for HE0435-1223, and 73.4$_{-4.4}^{+3.4}$ $λ_{\rm int}$ km s$^{-1}$ Mpc$^{-1}$ for WFI2033-4723. When combining the results from all three lenses, they obtain an overall H_0 value of 73.5$_{-2.8}^{+2.7}$ $λ_{\rm int}$ km s$^{-1}$ Mpc$^{-1}, which aligns closely with HST-based findings (73.6$_{-2.6}^{+2.6}$ $λ_{\rm int}$ km s$^{-1}$ Mpc$^{-1}), but with reduced variability across the systems. These newly developed lens models will be integrated into the TDCOSMO-2026 milestone paper utilizing a hierarchical approach with free $λ_{\rm int$. The researchers also outline how forthcoming JWST NIRCam targets will further refine uncertainties towards achieving percent-level precision in determining H_0.