Determination of Systemic velocities of galaxies from the analysis of atomic hydrogen in selected galaxies from the Atlas 3D survey

Abstract

I present the systemic velocities, which is one component of various galactic kinematics, for a sample of 2 galaxies NGC2685 and NGC4262. I obtained HI data of the ATLAS 3D survey from the public database of the Westerbork Radio Synthesis Telescope (WRST). I utilised a new astronomical analysis software, Cube Analysis and Rendering Tool for Astronomy (CARTA) to analyse the HI data cubes of the galaxies. During data analysis, I derived the HI global profiles for each galaxy and their moment zero and moment one maps. Using a double Gaussian, I fitted the global HI profiles and calculated the systemic velocity using the 20% and 50% line widths. I ascertained that galaxy NGC2685 had a lower systemic velocity of 873 km/s while galaxy NGC4262 had a systemic velocity of 1,356 km/s. I established that possible errors in my systemic velocities arose from the selection of the region of the target galaxies in the radio maps of the HI data cubes and the effects of instrumental broadening. I recommend a further study with a larger sample of galaxies and data reduction using advanced clipping techniques such as peak inspection based on the multichannel criterion to take out superior noise peaks well as data fitting using the Busy function.