JWST Photometric Time-Delay and Magnification Measurements for the Triply-Imaged Type Ia "Supernova H0pe" at z = 1.78

Abstract

Supernova (SN) H0pe is a gravitationally lensed, triply-imaged, Type Ia SN (SN Ia) discovered in James Webb Space Telescope imaging of the PLCK G165.7+67.0 cluster of galaxies. Well-observed multiply-imaged SNe provide a rare opportunity to constrain the Hubble constant ($H_0$), by measuring the relative time delay between the images and modeling the foreground mass distribution. SN H0pe is located at $z=1.783$, and is the first SN Ia with sufficient light curve sampling and long enough time delays for an $H_0$ inference. Here we present photometric time-delay measurements and SN properties of SN H0pe. Using JWST/NIRCam photometry we measure time delays of $\hat{I}”t_{ab}=-116.6_{-9.3}^{+10.8}$ and $\hat{I}”t_{cb}=-48.6_{-4.0}^{+3.6}$ observer-frame days relative to the last image to arrive (image 2b; all uncertainties are $1\ddot{I}ƒ$), which corresponds to a $\sim 5.6\%$ uncertainty contribution for $H_0$ assuming $70\mathrm{km}{\mathrm{s}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-1}$. We also constrain the absolute magnification of each image to $\hat{I}{¼}_a=4.3_{-1.8}^{+1.6}$, $\hat{I}{¼}_b=7.6_{-2.6}^{+3.6}$, $\hat{I}{¼}_c=6.4_{-1.5}^{+1.6}$ by comparing the observed peak near-IR magnitude of SN H0pe to the non-lensed population of SNe Ia.

Accepted in ApJ