[Skip to Content]

All galaxies with neutral hydrogen HI have been found to be forming new stars, which means they are actively evolving. Hence, HI selection is an ideal method to define the sequence of star forming galaxies. In this project the student will perform detailed measurements of the optical structure of thousands of HI selected galaxies from the HI Parkes All Sky Survey (HIPASS) using public large area sky surveys: PanSTARRS1, DES, SkyMapper – to give the optical structure; WISE for the mid- infrared structure, and GALEX for the ultraviolet structure. The PhD student will thus assemble this rich photometric dataset required to determine the distribution of stellar mass and star formation in the HIPASS sample. They will then analyse the data and map these quantities using a citizen scientist based computer network to do the most intensive analysis. The student will develop and apply new physically based models of how the gas and angular momentum in galaxies evolves to determine which evolutionary pathways are allowed between different types of dwarf galaxies, and will relate the results to cold-dark matter based models of how dwarf galaxies assemble and evolve. While similar datasets have been assembled on more distant samples (e.g. GAMA) here we will be able to determine the structure of galaxies in more detail and to much lower masses, and hence over a larger range of star forming galaxies.

Caption: The bottom panel shows the ultraviolet – optical colour as a function of optical luminosity of HI selected galaxies for a subsample of HIPASS. The blue and red lines show the location of the star forming and passive galaxy sequences determined for larger surveys of more distant galaxies (from the SDSS survey). Notice the HIPASS galaxies extend the sequence of more distant surveys, and that very few HIPASS galaxies have the colour of passive galaxies. The colour of the data points indicates a crude structural parameter, concentration, as indicated by the top panel.

Caption: The bottom panel shows the ultraviolet – optical colour as a function of optical luminosity of HI selected galaxies for a subsample of HIPASS. The blue and red lines show the location of the star forming and passive galaxy sequences determined for larger surveys of more distant galaxies (from the SDSS survey). Notice the HIPASS galaxies extend the sequence of more distant surveys, and that very few HIPASS galaxies have the colour of passive galaxies. The colour of the data points indicates a crude structural parameter, concentration, as indicated by the top panel.