A new H₀ measurement with SNe Requiem and Encore using Gravity.jl

@misc{bazzanini2026measurement,
  title = {{A new $H_0$ measurement with SNe Requiem and Encore using $\textttGravity.jl$}},
  author = {L. Bazzanini and G. Di Rosa and A. Acebron and P. Bergamini and M. Lombardi and P. Rosati and G. Angora and G. B. Caminha and S. Ertl and G. Granata and A. M. Koekemoer and S. H. Suyu and J. Pierel and A. B. Newman and C. Grillo and S. Schuldt and M. Bulla and S. Cha and M. D'Addona and J. M. Diego and M. Fogliardi and B. L. Frye and M. J. Jee and P. S. Kamieneski and M. Meneghetti and A. Mercurio and E. Vanzella},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2606.25205},
  eprint = {2606.25205},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2606.25205},
  note = {CC BY-SA 4.0},
}

TY  - UNPB
TI  - A new H_0 measurement with SNe Requiem and Encore using Gravity.jl
AU  - L. Bazzanini
AU  - G. Di Rosa
AU  - A. Acebron
AU  - P. Bergamini
AU  - M. Lombardi
AU  - P. Rosati
AU  - G. Angora
AU  - G. B. Caminha
AU  - S. Ertl
AU  - G. Granata
AU  - A. M. Koekemoer
AU  - S. H. Suyu
AU  - J. Pierel
AU  - A. B. Newman
AU  - C. Grillo
AU  - S. Schuldt
AU  - M. Bulla
AU  - S. Cha
AU  - M. D'Addona
AU  - J. M. Diego
AU  - M. Fogliardi
AU  - B. L. Frye
AU  - M. J. Jee
AU  - P. S. Kamieneski
AU  - M. Meneghetti
AU  - A. Mercurio
AU  - E. Vanzella
PY  - 2026
DA  - 2026/09/28
PB  - arXiv
DO  - 10.48550/arxiv.2606.25205
UR  - https://arxiv.org/abs/2606.25205
AB  - We present a strong-lensing (SL) analysis of the galaxy cluster MACS J0138.0-2155 (z=0.336), the first known lens cluster discovered to host two distinct multiply imaged Type Ia supernovae (SNe): SN Requiem and SN Encore. Both SNe are located in the massive, multiply imaged red galaxy MRG-M0138 at z=1.949. The projected total mass of this cluster has been investigated with several independent lens models (Suyu+26; Pierel+26), using a sample of 23 spectroscopically confirmed multiple images from 8 background sources (0.767<z<3.420), identified from HST and JWST imaging data, and VLT/MUSE spectroscopy. In this work, we develop a new SL model based on a novel Bayesian parametric lens-modelling framework Gravity jl, exploiting the same SL dataset. Our reference mass model accurately reproduces the observed image positions, with an image-plane rms image position residual of 0.15''. Assuming H0 = 70 km/s/Mpc, we predict the future reappearances of highly delayed SNe counter-images, finding D_t(1d,1a) = 3122_−70^+75 d (April-August 2032) for SN Encore and D_t(2d,2a) = 3902_−67^+72 d (January-May 2027) for SN Requiem. By allowing H0 to vary, and using the measured time delays of SN Encore and Requiem together with their statistical uncertainties as observables, we infer the value of H0 jointly with the other lens-model free parameters, by combining the values inferred from 3 mass models. We obtain a new measurement of H_0 = 69.2_−8.0^+9.6 km/s/Mpc, consistent with the value inferred from independent lens models. This error is currently dominated by the large relative uncertainty on the measured time delays (>10%). The forthcoming reappearance of SN Requiem offers an immediate opportunity to significantly improve constraints on H0, provided that lens-model systematics are controlled. These results establish M0138 as a premier anchor for high-precision cluster TDC.
ER  -