TDCOSMO 2026: new insights on the Hubble tension from strong lensing time delays

TDCOSMO Collaboration; Simon Birrer; Michele Cappellari; Frédéric Courbin; Christopher D. Fassnacht; Pierre Fleury; Joshua A. Frieman; Aymeric Galan; Xiang-Yu Huang; Daniel P. Johnson; Sanjana Khanolkar; Shawn Knabel; Hrvoje Krizic; Martin Millon; Takahiro Morishita; Veronica Motta; Pritom Mozumdar; Eric Paic; Hadrien Paugnat; Allan G. Schweinfurth; Anowar J. Shajib; William Sheu; Dominique Sluse; Massimo Stiavelli; Sherry H. Suyu; Tommaso Treu; Felipe Urcelay; Devon M. Williams; Kenneth C. Wong

arXiv · 2610.14881

TDCOSMO 2026: new insights on the Hubble tension from strong lensing time delays

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Abstract

We discuss the measurement of the Hubble constant ($H_0$) in flat $Λ$ cold dark matter cosmology based on the blind hierarchical analysis of 11 multiply-imaged quasars (hereafter the TDCOSMO-2026 sample) and described in greater detail in a companion paper. In addition to the time delays, we use lens models based on high-resolution imaging from the Hubble Space Telescope (HST) and from the James Webb Space Telescope (JWST), analyzed jointly with axisymmetric dynamical models based on JWST-NIRSpec, VLT-MUSE, and Keck-KCWI spectroscopy. Our primary result $H_0=71.1^{+2.4}_{-2.3}$ km.s$^{-1}$.Mpc$^{-1}$ is based on the TDCOSMO-2026 sample, in combination with $Ω_{\rm m}$ constraints from the DES-Dovekie supernova (SN) dataset. Our 3% precision accounts for the mass-sheet degeneracy. Importantly, our measurement is independent of the local distance ladder (LDL). Among individual late-universe probes, only the traditional LDL is more precise. We discuss our result in the context of the Hubble tension, the difference between $H_0$ measured in the late universe and the prediction based on early-universe probes such as the cosmic microwave background (CMB). We construct combinations of independent late-universe probes and show that the tension with the Planck CMB prediction is robust to excluding any one of the methods based on Type-Ia Supernovae, Cepheids, or the Tip of the Red Giant Branch. For example, we construct a 'no-SN' $H_0$ measurement, by replacing the DES-Dovekie constraint on $Ω_{\rm m}$ with that from DESI baryon acoustic oscillations, and then combining TDCOSMO-2026 with independent non-SN late-universe probes. This 'no-SN' late-universe probe is in 3.7$σ$ tension with Planck. Even after completely excluding the LDL, the tension with Planck persists at the 2.7$σ$ level.

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TDCOSMO Collaboration, Simon Birrer, Michele Cappellari, Frédéric Courbin, Christopher D. Fassnacht, Pierre Fleury, Joshua A. Frieman, Aymeric Galan, Xiang-Yu Huang, Daniel P. Johnson, Sanjana Khanolkar, Shawn Knabel, Hrvoje Krizic, Martin Millon, Takahiro Morishita, Veronica Motta, Pritom Mozumdar, Eric Paic, Hadrien Paugnat, Allan G. Schweinfurth, Anowar J. Shajib, William Sheu, Dominique Sluse, Massimo Stiavelli, Sherry H. Suyu, Tommaso Treu, Felipe Urcelay, Devon M. Williams, Kenneth C. Wong. 2026-10-10. TDCOSMO 2026: new insights on the Hubble tension from strong lensing time delays. https://arxiv.org/abs/2610.14881

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