HI Asymmetries in LVHIS, VIVA and HALOGAS Galaxies
  We present an analysis of morphological, kinematic and spectral asymmetries
in observations of atomic neutral hydrogen (HI) gas from the Local Volume HI
Survey (LVHIS), the VLA Imaging of Virgo in Atomic Gas (VIVA) survey and the
Hydrogen Accretion in Local Galaxies Survey (HALOGAS). With the aim of
investigating the impact of the local environment density and stellar mass on
the measured HI asymmetries in future large HI surveys, we provide
recommendations for the most meaningful measures of asymmetry for use in future
analysis. After controlling for stellar mass, we find signs of statistically
significant trends of increasing asymmetries with local density. The most
significant trend we measure is for the normalised flipped spectrum residual
($A_{\mathrm{spec}}$), with mean LVHIS and VIVA values of $0.204\pm0.011$ and
$0.615\pm0.068$ at average weighted $10^{\mathrm{th}}$ nearest-neighbour galaxy
number densities of $\log(\rho_{10}/\mathrm{Mpc}^{-3})=-1.64$ and 0.88,
respectively. Looking ahead to the WALLABY survey on the Australian Square
Kilometre Array Pathfinder (ASKAP), we estimate that the number of detections
will be sufficient to provide coverage over 5 orders of magnitude in both local
density and stellar mass increasing the dynamic range and accuracy with which
we can probe the effect of these properties on the asymmetry in the
distribution of atomic gas in galaxies.
