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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 $0.204pm0.011$ and $0.615pm0.068$ 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.
We present a systematic study of the extraplanar gas (EPG) in a sample of 15 nearby late-type galaxies at intermediate inclinations using publicly available, deep interferometric HI data from the HALOGAS survey. For each system we mask the HI emissio
The `Local Volume HI Survey (LVHIS) comprises deep HI spectral line and 20-cm radio continuum observations of 82 nearby, gas-rich galaxies, supplemented by multi-wavelength images. Our sample consists of all galaxies with Local Group velocities v_LG
We present 21-cm observations and models of the HI kinematics and distribution of NGC 4244, a nearby edge-on Scd galaxy observed as part of the Westerbork Hydrogen Accretion in LOcal GAlaxieS (HALOGAS) survey. Our models give insight into the HI kine
We present 21-cm observations and models of the neutral hydrogen in NGC 4565, a nearby, edge-on spiral galaxy, as part of the Westerbork Hydrogen Accretion in LOcal GAlaxieS (HALOGAS) survey. These models provide insight concerning both the morpholog
Observations of the cold neutral atomic hydrogen (HI) in and around disc galaxies have revealed that spatial and kinematic asymmetries are commonplace, and are reflected in the global HI spectra. We use the TNG100 box from the IllustrisTNG suite of c