A Generalist, Automated ALFALFA Baryonic Tully–Fisher Relation

Abstract

The baryonic Tully–Fisher relation (BTFR) has applications in galaxy evolution as a test bed for the galaxy–halo connection and in observational cosmology as a redshift-independent secondary distance indicator. This analysis leverages the 31,000+ galaxy Arecibo Legacy Fast ALFA (Arecibo L -band Feed Array) Survey (ALFALFA) sample—which provides redshifts, velocity widths, and H i content for a large number of gas-bearing galaxies in the local universe—to fit and test an extensive local universe BTFR. The fiducial relation is fit using a 3000-galaxy subsample of ALFALFA, and is shown to be consistent with the full sample. This BTFR is designed to be as inclusive of ALFALFA and comparable samples as possible. Velocity widths measured via an automated method and M _b proxies extracted from survey data can be uniformly and efficiently measured for other samples, giving this analysis broad applicability. We also investigate the role of sample demographics in determining the best-fit relation. We find that the best-fit relations are changed significantly by changes to the sample mass range and to second order by changes to mass sampling, gas fraction, different stellar mass and velocity width measurements. We use a subset of ALFALFA with demographics that reflect the full sample to measure a robust BTFR slope of 3.30 ± 0.06. We apply this relation and estimate source distances, finding general agreement with flow-model distances as well as average distance uncertainties of ∼0.17 dex for the full ALFALFA sample. We demonstrate the utility of these distance estimates by applying them to a sample of sources in the Virgo vicinity, recovering signatures of infall consistent with previous work.

Keywords

• Galactic and extragalactic astronomy
• Galaxy distances
• H I line emission
• Galaxy dynamics
• Spiral galaxies