2021/10/07 by Brownsberger, Sasha, Brout, Dillon, Scolnic, Daniel +2
#Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2110.03486
Type Ia supernovae (SNe Ia) measurements of the Hubble constant, H0, the cosmological mass density, ΩM, and the dark energy equation-of-state parameter, w, rely on numerous SNe surveys using distinct photometric systems across three decades of observation. Here, we determine the sensitivities of the upcoming SH0ES+Pantheon+ constraints on H0, ΩM, and w to unknown systematics in the relative photometric zeropoint calibration between the 17 surveys that comprise the Pantheon+ supernovae data set. Varying the zeropoints of these surveys simultaneously with the cosmological parameters, we determine that the SH0ES+Pantheon+ measurement of H0 is robust against inter-survey photometric miscalibration, but that the measurements of ΩM and w are not. Specifically, we find that miscalibrated inter-survey systematics could represent a source of uncertainty in the measured value of H0 that is no larger than 0.2 km s-1 Mpc-1. This modest increase in H0 uncertainty could not account for the 7 km s-1 Mpc-1 "Hubble Tension" between the SH0ES measurement of H0 and the Planck ΛCDM-based inference of H0. However, we find that the SH0ES+Pantheon+ best-fit values of ΩM and w respectively slip, to first order, by 0.04 and -0.17 per 25 mmag of inter-survey calibration uncertainty, underscoring the vital role that cross-calibration plays in accurately measuring these parameters. Because the Pantheon+ compendium contains many surveys that share low-z Hubble Flow and Cepheid-paired SNe, the SH0ES+Pantheon+ joint constraint of H0 is robust against inter-survey photometric calibration errors, and such errors do not represent an impediment to jointly using SH0ES+Pantheon+ to measure H0 to 1% accuracy.