Uncertainties in the Hubble Constant from Peculiar Velocities

TL;DR

This paper quantifies the uncertainty in the Hubble constant measurement due to peculiar velocity corrections, finding it to be smaller than the total uncertainty, thus supporting current measurement reliability.

Contribution

It introduces a mock universe approach to accurately estimate the uncertainty from peculiar velocity reconstructions in H0 measurements.

Findings

Uncertainty from peculiar velocity correction is about 0.3 km/s/Mpc.

This uncertainty is smaller than the total H0 measurement uncertainty.

Supports the robustness of current H0 measurement methods.

Abstract

Recent measurements of the Hubble constant using type Ia supernovae explicitly correct for their estimated peculiar velocities using the 2M++ reconstruction of the local density field. The amount of uncertainty from this reconstruction procedure has thus far been unquantified. To rectify this, we use mock universe realisations of the 2M++ catalogue and generate predicted peculiar velocities using the same method as the predictions that are used to correct for the Pantheon+ catalogue. We find that the method yields uncertainties of 0.3 km/s/Mpc and hence subdominant to the total uncertainty in H0.