WALLABY Pilot Survey: Gas-Rich Galaxy Scaling Relations from Marginally-Resolved Kinematic Models

TL;DR

This paper presents the first galaxy scaling relations derived from kinematic models of WALLABY pilot survey data, providing a large, uniform sample for studying HI properties and their relation to galaxy dynamics.

Contribution

It introduces a framework for measuring HI structural properties from kinematic models and applies it to the largest untargeted HI survey sample to date.

Findings

Scaling relations similar to previous HI surveys.

Largest sample of galaxy properties from an untargeted HI survey.

Consistent optical and kinematic inclinations used for Tully-Fisher analysis.

Abstract

We present the first set of galaxy scaling relations derived from kinematic models of the Widefield ASKAP L-band Legacy All-sky Blind surveY (WALLABY) pilot phase observations. Combining the results of the first and second pilot data releases, there are 236 available kinematic models. We develop a framework for robustly measuring HI disk structural properties from these kinematic models; applicable to the full WALLABY survey. Utilizing this framework, we obtained the HI size, a measure of the rotational velocity, and angular momentum for 148 galaxies. These comprise the largest sample of galaxy properties from an untargetted, uniformly observed and modelled HI survey to date. We study the neutral atomic Hydrogen (HI) size-mass, size-velocity, mass-velocity, and angular momentum-mass scaling relations. We calculate the slope, intercept, and scatter for these scaling relations and find that they are similar to those obtained from other HI surveys. We also obtain stellar masses for 92 of the 148 robustly measured galaxies using multiband photometry through the Dark Energy Sky Instrument Legacy Imaging Survey Data Release-10 images. We use a subset of 61 of these galaxies that have consistent optical and kinematic inclinations to examine the stellar and baryonic Tully Fisher relations, the gas fraction-disk stability and gas fraction-baryonic mass relations. These measurements and relations demonstrate the unprecedented resource that WALLABY will represent for resolved galaxy scaling relations in HI.