| Summary: | The work in this thesis aims to accurately determine the gas kinematics in disc galaxies and relate those inferences to their drivers. For this thesis a Bayesian disc modelling technique, known as Blobby3D, was developed to infer the gas kinematics of galaxies while limiting the effects of beam smearing. Blobby3D was applied to samples of galaxies from the SAMI Galaxy Survey, DYnamics of Newly Assembled Massive Objects (DYNAMO) survey, and the KMOS Redshift One Spectroscopic Survey (KROSS). The results of these analyses were used to gain accurate measures of the velocity dispersion and rotational velocity in galaxies from z ~ 0.1 to z ~ 1 with wide ranging galaxy properties. Using these results it was found that the gas velocity dispersion in galaxies at z ~ 0.1 slowly increases from σ ~ 17±3 km/s to σ ~ 24±5 km/s across the range log(SFR/ M/yr) in [-3, 0]. A sharper increase in velocity dispersion occurs for log(SFR/ M/yr) > 0, where the velocity dispersion increases to as high as σ ~ 80 km/s. The SFR–σ relation was found to be consistent with turbulence driven by models that incorporated both star-formation feedback processes and gravitational transport of gas through the disc. Comparisons of the results from KROSS at z ~ 1 to those from the SAMI Galaxy Survey and DYNAMO survey were used to determine the change in gas kinematics across epochs. The typical velocity dispersion at z ~ 1 was found to be consistent with galaxies from the DYNAMO survey that have similar galaxy properties. This suggests that the galaxy properties are playing a major factor in the intrinsic velocity dispersion of the galaxy. It was then shown that disc galaxies are consistent with being marginally stable from gravitational collapse. The consistency of SFR-σ with the theoretical models that include star-formation feedback and gas transport are also shown to extend to galaxies at z ~ 1. The usefulness and future applicability of using Blobby3D in future studies is then outlined in the conclusion.
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