The Chicago Carnegie Hubble Program: Improving the Calibration of SNe Ia with JWST Measurements of the Tip of the Red Giant Branch (2503.11769v1)

Abstract: We present distances to ten supernova (SN) host galaxies determined via the red giant branch tip (TRGB) using JWST/NIRCAM and the F115W, F356W, and F444W bandpasses. Our analysis, including photometric catalog cleaning, adoption of disk light profiles, TRGB color slope estimation, and a novel technique for identifying the infrared TRGB, was conducted blinded. The new F115W TRGB distances agree well with our previously derived HST TRGB distances, differing by only 1 percent on average and 4 percent on a per-galaxy basis. The color-corrected F115W TRGB is therefore equally precise a method of distance measurement as, and offers unique advantages over, its color-insensitive, I-band counterpart. Using these distances, we update the absolute calibrations of eleven calibrator SNe, yielding 68.4 < H0 < 69.6 km/s/Mpc depending on which of four sets of SN magnitudes are used. We expand the sample of calibrator SNe to 24 by combining with HST TRGB distances. Doing so increases our H0 estimate based on the Carnegie Supernova Project II (CSP-II) by 0.8 km/s/Mpc (1.4 sigma) demonstrating that our JWST H0 based on 11 SNe is not significantly biased toward lower values. In contrast, the Pantheon+ calibration shifts higher by +2 km/s/Mpc (3.1 sigma), a significantly larger increase than seen in both the CSP and the Pantheon team's own SuperCal analysis. More JWST observations of the TRGB as well as independent analyses of low-redshift SNe are needed to continue unraveling the true nature of the Hubble Tension.