A new technique to isolate kinematically anomalous gas in HI data cubes

Abstract

H I line observations of nearby galaxies often reveal the presence of extraplanar and/or kinematically anomalous gas that deviates from the general circular flow. In this work, we study the dependence of kinematically anomalous H I gas in galaxies taken from the SIMBA cosmological simulation on galaxy properties such as H I mass fraction, specific star formation rate, and local environmental density. To identify kinematically anomalous gas, we use a simple yet effective decomposition method to separate it from regularly rotating gas in the galactic disc; this method is well-suited for application to observational data sets but has been validated here using the simulation.