The Local Volume HI Survey: Galaxy Kinematics

TL;DR

This paper analyzes the neutral hydrogen kinematics of 12 nearby dwarf irregular galaxies, measuring their disk parameters and rotation curves, and compares these with survey data to understand galaxy dynamics and the Tully-Fisher relation.

Contribution

It provides detailed HI kinematic measurements for 12 galaxies, including first-time studies for six, and discusses the conditions for using 21cm line profiles to estimate galaxy rotation velocities.

Findings

Six galaxies studied for the first time in HI distribution.

Evidence of tidal interaction in AM0605-341.

Discussion on the accuracy of 21cm line profiles for rotation velocity.

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 (LVHIS) conducted at the Australia Telescope Compact Array. For each galaxy we measure the disk 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, 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 (HIPASS). We discuss under what circumstances the 21cm emission line profile can accurately predict the galaxy's rotation velocity, an observational parameter crucial to study the classical and baryonic Tully-Fisher relations.