Cosmicflows-4: The Baryonic Tully-Fisher Relation Providing ~10,000 Distances

TL;DR

This paper uses the baryonic Tully-Fisher relation to measure distances to nearly 10,000 galaxies, providing a new estimate of the Hubble constant with statistical uncertainty.

Contribution

It presents a large-scale application of the baryonic Tully-Fisher relation for galaxy distance measurement and calibrates it with Cepheid and red giant branch star data.

Findings

Distances for 9984 galaxies were obtained.

The Hubble constant is estimated at 75.5 km/s/Mpc.

The method accounts for HI selection bias.

Abstract

The interstellar gas in spiral galaxies can constitute a significant fraction of the baryon mass and it has been demonstrated that the sum of stellar and gas components correlates well with the kinematic signature of the total mass content, the widths of HI line profiles. The correlation of baryonic mass with HI line widths is used here to obtain distances for 9984 galaxies extending to ~0.05c. The sample is HI flux limited and a correction is required to account for an HI selection bias. The absolute scale is established by 64 galaxies with known distances from studies of Cepheid variables and/or the magnitudes of stars at the tip of the red giant branch. The calibration of the baryonic relationship results in a determination of the Hubble constant of H_0=75.5+-2.5 km/s/Mpc. The error estimate is statistical. This material will be combined with contributions from other methodologies in a subsequent article where systematic uncertainties will be investigated.