The Hubble constant from the improved lens modeling of cluster-lensed supernova Refsdal with new spectroscopic redshifts and the Jackknife method

TL;DR

The paper uses time-delay cosmography of the cluster-lensed SN Refsdal in MACS J1149.5+2223, enhanced by new spectroscopic redshifts from VLT/MUSE and JWST CANUCS/Technicolor, and validates lens models with a Jackknife approach. Analyzing four lens mass models (NFW and PJE halos with external perturbations) yields a combined Hubble constant of $H_0 = 66.0^{+4.3}_{-4.3}$ km s$^{-1}$ Mpc$^{-1}$, with individual models spanning $64.2$ to $69.3$ km s$^{-1}$ Mpc$^{-1}$. The results are robust to modeling choices and align with Planck-era constraints, supporting time-delay cosmography as a competitive independent probe of $H_0$ while acknowledging unaccounted mass-sheet and line-of-sight systematics. The study demonstrates the value of richer spectroscopic constraints and rigorous model validation for cluster-scale lensing in precision cosmology.

Abstract

Time-delay cosmology offers an alternative approach to measuring the Hubble constant ($H_0$), which is distinct from the cosmic distance ladder and cosmic microwave background radiation methods. In this study, we present an improved strong lens mass modeling analysis of the cluster-lensed supernova Refsdal, incorporating the latest spectroscopic redshift data from the MUSE on the Very Large Telescope and the James Webb Space Telescope CANUCS/Technicolor. The robustness of our lens models is confirmed using the Jackknife method. From our analysis that considers four lens mass models with different assumptions on profiles of dark matter halos and external perturbations, we derive a constraint on the Hubble constant of $H_0=66.0\pm{4.3}\Mpc$ after combining best-fitted values of the four lens models.

Figures (3)

• Figure 1: The Jackknife distributions for all four different lens mass models with 4$\sigma$ outliers removed ( purple), along with the standard normal distribution ( pink). The upper panel from left to right are the model m1 and m2. The lower panel from left to right are the model m3 and m4.
• Figure 2: The spatial distribution of $\Delta=\sqrt{(\Delta x/\sigma)^2+(\Delta y/\sigma)^2}$ for all 4 different lens mass models. The position ($X_{\rm obs}$, $Y_{\rm obs}$) refers to the image plane position with respect to the cluster center. The upper panel from left to right are the model m1 and m2. The lower panel from left to right are the model m3 and m4.
• Figure 3: The probability distribution functions (PDFs) for the Hubble constant, corresponding to each of the four distinct lens mass models, are illustrated with dashed lines. The solid line represents the PDF resulting from the equal-weighted combination of all the four models. The vertical orange dotted lines and the shaded area denote the median and the 68.3% confidence interval of the combined PDF.