2021ApJ...907...35B

We explore the properties of supernova (SN) "Refsdal"-the first discovered gravitationally lensed SN with multiple images. A large magnification provided by the galactic-scale lens, augmented by the cluster lens, gave us a unique opportunity to perform a detailed modeling of a distant SN at z≃1.5. We present results of radiation hydrodynamics modeling of SN Refsdal. According to our calculations, the SN Refsdal progenitor is likely to be a more massive and energetic version of SN 1987A, i.e., a blue supergiant star with the following parameters: the progenitor radius R₀=(50±1)R_☉, the total mass M_tot=(25±2)M_☉, the radioactive ⁵⁶Ni mass M_^56Ni=(0.26±0.05)M_☉, and the total energy release E_burst=(4.7±0.8)×10⁵¹ erg. Reconstruction of SN light curves allowed us to obtain time delays and magnifications for the images S2-S4 relative to S1 with higher accuracy than previous template-based estimates of Rodney et al. (2016). The measured time delays are Δt_S2–S1=9.5_–2.7^+2.6 days, Δt_S3–S1=4.2_–2.3^+2.3 days, and Δt_S4–S1=30_–8.2^+7.8 days. The obtained magnification ratios are µ_S2/S1=1.14±0.02, µ_S3/S1=1.01±0.02, and µ_S4/S1=0.35±0.02. We estimate the Hubble constant H₀=68.6_–9.7^+13.6 km s^–1 Mpc^–1 via rescaling the time delays predicted by different lens models to match the values obtained in this work. With more photometric data on the fifth image SX, we will be able to further refine the time delay and magnification estimates for SX and obtain competitive constraints on H₀.