Using EAGLE simulations to study the effect of observational constraints on the determination of HI asymmetries in galaxies

We investigate the effect of observational constraints such as signal-to-noise, resolution and column density level on the HI morphological asymmetry (\(\mathrm{A}_\mathrm{mod}\)) and the effect of noise on the HI global profile (\(\mathrm{A}_\mathrm{flux}\)) asymmetry indices. Using mock galaxies from the EAGLE simulations we find an optimal combination of the observational constraints that are required for robust measurement of the \(\mathrm{A}_\mathrm{mod}\) value of a galaxy: a column density threshold of \(5\times10^{19}cm^{-2}\) or lower at a minimal signal-to-noise of 3 and a galaxy resolved with at least 11 beams. We also use mock galaxies to investigate the effect of noise on the \(\mathrm{A}_\mathrm{flux}\) values and conclude that a global profile with signal-to-noise ratio greater than 5.5 is required to achieve a robust measurement of asymmetry. We investigate the relation between \(\mathrm{A}_\mathrm{mod}\) and \(\mathrm{A}_\mathrm{flux}\) indices and find them to be uncorrelated which implies that \(\mathrm{A}_\mathrm{flux}\) values cannot be used to predict morphological asymmetries in galaxies.