Modelling Local Galaxy HI Disks With WALLABY Pilot Phase 2

Abstract

Neutral atomic hydrogen, HI, is a readily available observable tracer of atomic gas in the universe. The model reliability for HI detections in recovering the rotation curve from kinematic models has been previously studied, but this has not been done for the surface density profiles. This thesis investigates the reliable recovery of the surface density profiles and HI radius, R$_{HI}$ from the Pilot Phase 2 of the Widefield ASKAP L-band Legacy All-sky surveY (WALLABY) detections from the Australian SKA Pathfinder (ASKAP) telescope. The surface density profiles and R$_{HI}$ were measured using a nested tilted ring modelling method on mock WALLABY observations to determine the regime in which these characteristics are reliably recovered. The kinematic modeling previously completed for the WALLABY Public Data Release 1 (PDR1) was then completed for WALLABY Pilot Phase 2 data (Phase 2). The results from the kinematic modeling were compared to quantify the modeling results (attempted models, successful models, failed models). The results from the kinematic models for the Phase 2 data are used to construct scaling relations: HI size-mass, and the HI size-velocity. The derived HI size-mass relation follows a tight correlation as expected from previous investigations. The HI size-velocity relation constructed is among the first ever for an untargetted HI survey, and demonstrates the potential of WALLABY to constrain the structure of populations of HI disks.