The Local Volume Hi Survey: Galaxy kinematics

Abstract

We present a detailed analysis of the neutral hydrogen kinematics of 12 nearby dwarf irregular galaxies observed as part of the Local Volume Hi Survey conducted at the Australia Telescope Compact Array. For each galaxy we measure the disc parameters (inclination, position angle) and the Hi rotation curve. Six galaxies in our sample (AM0605-341, Argo Dwarf, ESO059-G001, ESO137-G018, ESO174-G?001 and ESO308-G022) have their atomic hydrogen distribution studied for the first time. AM0605-341 was found to have an extension of redshifted Hi which we propose is due to a tidal interaction with NGC2188. There is evidence that ESO215-G?009 has extraplanar Hi gas. We also compare the global galaxy properties, in particular the integrated Hi flux density and velocity widths of the observed Hi spectra, with the results from the low angular resolution Hi Parkes All Sky Survey. We discuss under what circumstances the 21cm emission-line profile can accurately predict the galaxies rotation velocity, an observational parameter crucial to study the classical and baryonic Tully-Fisher relations.