The Hubble constant from SN Refsdal

TL;DR

This paper measures the Hubble constant using time delays from the first lensed supernova in a galaxy cluster, achieving results consistent with other cosmological methods and highlighting the potential of this approach for future constraints.

Contribution

It presents the first H_0 measurement from time delays of a lensed supernova in a galaxy cluster, demonstrating a novel method with promising future applications.

Findings

H_0 = 64^{+9}_{-11} km/s/Mpc (68% CL)

First H_0 constraint from a lensed supernova in a galaxy cluster

Results agree with CMB and other large-scale structure measurements

Abstract

Hubble Space Telescope observations from December 11 2015 detected the expected fifth counter image of SN Refsdal at $z = 1.49$. In this letter, we compare the time delay predictions from numerous models with the measured value derived by \citet{Kelly2016a} from very early data in the light curve of the SN Refsdal, and find a best value for $H_0 = 64^{+9}_{-11}~\mathrm{km~s^{-1}~Mpc^{-1}}$ (68\% CL), in excellent agreement with predictions from CMB and recent weak lensing data + BAO + BBN (from the DES Collaboration). This is the first constraint on $H_0$ derived from time delays between multiple lensed SN images, and the first with a galaxy cluster lens, so subject to systematic effects different from other time-delay $H_0$ estimates. Additional time delay measurements from new multiply-imaged SNe will allow derivation of competitive constraints on $H_0$.