James Webb Space Telescope Feed Post

SN H0pe: The First Measurement of H0 from a Multiply-Imaged Type Ia Supernova, Discovered by JWST

Left: JWST/NIRCam color image in the central region of PLCK G165.7+67.0 from PEARLS (epoch 1). The filters used are F090W (blue), F200W (green), and F444W (red). The images were drizzled to 0?.''?03/pix, and the image scale and orientation are as shown. Right: Closeup of the boxed region depicting the three images of the galaxy Arc 2, as labeled. SN H0pe (circled) appears in all three images and flips parity between images 2c and 2b and between images 2b and 2a, as predicted by lensing theory. 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 (H0), 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 H0 inference. Here we present photometric time-delay measurements and SN properties of SN H0pe. Using JWST/NIRCam photometry we measure time delays of ?tab=-116.6+10.8-9.3 and ?tcb=-48.6+3.6-4.0 observer-frame days relative to the last image to arrive (image 2b; all uncertainties are 1s), which corresponds to a ~5.6% uncertainty contribution for H0 assuming 70kms-1Mpc-1. We also constrain the absolute magnification of each image to µa=4.3+1.6-1.8, µb=7.6+3.6-2.6, µc=6.4+1.6-1.5 by comparing the observed peak near-IR magnitude of SN H0pe to the non-lensed population of SNe Ia.