Wednesday

What happens to the morphology of a galaxy when it uses up all of its gas? How do galaxies transition from the blue cloud to the red sequence? Should this transition phase be considered distinct and what does this tell us about the role of morphology in galaxy evolution?
I present the results of an exploratory study into the morphologies of galaxies located in, and either side of, the 'green valley'. Using data from the Galaxy And Mass Assembly (GAMA) survey, imaging from the VST Kilo-Degree Survey (KiDS), and harnessing the crowd-sourcing capabilities of the Zooniverse project, we show how various morphological indicators vary as a function of mass and colour for a sample of ~400 M* galaxies in the local Universe. We find that galaxies in transition from blue to red show distinctive structural markers, including a surplus of rings and bars. Not only does this highlight the peculiar nature of galaxies in this regime, but it hints at the dominant mode of blue-red transformation for Milky-Way mass galaxies, namely, a passive transformation linked to the slow inside-out death of star formation.