Milky Way Analogues through the Lens of Integral Field Spectroscopy: A Systematic Approach to Galaxy Kinematics

Abstract

In this thesis, we determine the properties of Milky Way Analogues (MWAs) using different selection techniques for identifying MWAs in the SAMI Galaxy Survey to place the Milky Way in cosmological perspective. We define MWAs using a nearest neighbours method with four selection parameters: stellar mass, star formation rate (SFR), bulge-to-total ratio (B/T) and disc effective radius. Our results show that stellar mass and SFR are the most important parameters that minimise biases towards lower stellar masses and lower SFRs in the average MWA properties as compared to the Milky Way. Selection combinations without disc effective radius, result in MWAs that are too large in size due to the Milky Way's smaller-than-average size. We find that B/T is the least important parameter out of the four tested parameters. By defining the top-10 MWAs in field and cluster environments, we find that a typical MWA is a barred spiral, with a kinematically cold rotating disc, and resides in a wide range of environments.

We then investigate the effects of instrumental spectral resolution on measuring the stellar kinematics of galaxies in the Hector Galaxy Survey, a new multi-object integral field spectrograph that was developed based on the design of the SAMI Galaxy Survey. We perform a detailed analysis of the spectral resolution and use this to study the kinematics of the first galaxy sample observed with Hector. We find that the line spread function (LSF) depends on both wavelength and hexabundle. For the most accurate stellar kinematic measurements, we therefore recommend using an arc-line based LSF that incorporates variation with wavelength and hexabundle. We find that with Hector we can measure the spin parameter in galaxies with stellar masses as low as log(M/M_Sun)~8.4. While the median spin parameter remains mostly constant around 0.4 between 9.0<log(M/M_Sun)<11.0, we find a decline in spin parameter at log(M/M_Sun)<9.0.