James Webb Space Telescope Feed Post

Arxiv: The JWST Discovery of the Triply-imaged Type Ia "Supernova H0pe" and Observations of the Galaxy Cluster PLCK G165.7+67.0 Published: 9/14/2023 12:40:01 AM Updated: 12/4/2023 9:17:01 PM

Paper abstract: A Type Ia supernova (SN) at z=1.78 was discovered in James Webb SpaceTelescope Near Infrared Camera imaging of the galaxy cluster PLCK G165.7+67.0(G165; z = 0.35). The SN is situated 1.5-2 kpc from the host-galaxy nucleusand appears in three different locations as a result of gravitational lensingby G165. These data can yield a value for Hubble's constant using time delaysfrom this multiply-imaged SN Ia that we call "SN H0pe." Over the cluster, weidentified 21 image multiplicities, confirmed five of them using theNear-Infrared Spectrograph, and constructed a new lens model that gives a totalmass within 600 kpc of (2.6 \pm 0.3) \times 10^{14} M_{\odot}. Thephotometry uncovered a galaxy overdensity coincident with the SN host galaxy.NIRSpec confirmed six member galaxies, four of which surround the SN hostgalaxy with relative velocity <~900 km s^{-1} and projected physicalextent <~33 kpc. This compact galaxy group is dominated by the SN hostgalaxy, which has a stellar mass of (5.0 \pm 0.1) \times 10^{11} M_{\odot}.The group members have specific star-formation rates of 2-260 Gyr^{-1}derived from the H\alpha-line fluxes corrected for stellar absorption, dustextinction, and slit losses. Another group centered on a strongly-lensed dustystar forming galaxy is at z=2.24. The total (unobscured and obscured) SFR ofthis second galaxy group is estimated to be (\gtrsim100 M_{\odot}yr^{-1}), which translates to a supernova rate of ~1 SNe yr^{-1},suggesting that regular monitoring of this cluster may yield additional SNe.