The Hubble constant from SN Refsdal

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 $H_0=64_{-11}^{+9}\mathrm{km}{\mathrm{s}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-1}$ (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 $H_0$.

6 pages, 2 figures. Accepted for publication in ApJL