Probing the HI Kinematics of the LMC: Toward Interpreting QAL Observations of Protogalactic Velocity Fields

Abstract

We examine the gas kinematics of the LMC revealed by the high spatial and velocity resolution HI data cube of the combined ATCA and Parkes telescope surveys. We adopt an approach designed to facilitate comparisons with quasar absorption line observations, in particular restricting our analysis to pointings with HI column density satisfying the damped Lya (DLA) criterion. We measure velocity widths for ~5000 random pointings to the LMC and find a median value of ~40 km/s which modestly exceeds the value predicted by differential rotation. This median is significantly lower than the median value observed for the metal-line profiles of high z DLA. Therefore, assuming