The Hubble Tension Revisited: Additional Local Distance Ladder Uncertainties

TL;DR

This paper revisits uncertainties in the local distance ladder, including Cepheid and supernova parameters, and finds that accounting for these uncertainties can reduce the Hubble tension between local and CMB measurements.

Contribution

It provides a comprehensive analysis of additional sources of uncertainty in the supernova distance ladder and demonstrates their impact on the Hubble constant estimate.

Findings

Including various uncertainties yields H0 = 71.9±2.2 km/s/Mpc.

Excluding certain Cepheids reduces H0 to 68.1±2.6 km/s/Mpc.

Accounting for uncertainties can alleviate the Hubble tension.

Abstract

In a recent paper, we investigated possible systematic uncertainties related to the Cepheid color-luminosity calibration method and their influence on the tension between the Hubble constant as inferred from distances to Type Ia supernovae and the cosmic microwave background as measured with the Planck satellite. Here, we study the impact of other sources of uncertainty in the supernova distance ladder, including Cepheid temperature and metallicity variations, supernova magnitudes and GAIA parallax distances. Using Cepheid data in 19 Type Ia supernova host galaxies from Riess et al (2016), anchor data from Riess et al (2016, 2019, 2021) and a set of re-calibrated Milky Way Cepheid distances, we obtain $H_0 = 71.9\pm 2.2$ km/s/Mpc, $2.0\,\sigma$ from the Planck value. Excluding Cepheids with estimated color excesses $\hat{E}({\rm V} - {\rm I})=0.15$ mag to mitigate the impact of the Cepheid color-luminosity calibration, the inferred Hubble constant is $H_0 = 68.1\pm 2.6$ km/s/Mpc, removing the tension with the Planck value.