Shedding Light on the Growth of Galaxies Through Dark Matter Halo Occupation

Résumé du livre

Galaxies can be separated into two broad classes; those actively forming stars (star-forming) and those with little-to-no ongoing star formation (passive). A key question of galaxy evolution is, how is star formation shut down in galaxies? As passive galaxies are predominantly more massive than their star-forming counterparts, and contain H"50% of the stellar mass in the present Universe, their formation history gives insight into the formation mechanisms for all galaxies. How did they form? How and why was their star formation shut down? Colour can be used as a rough proxy for these two classes of galaxy. Galaxies that largely emit red light are made up of an older stellar population and are thereby passive. Whereas galaxies that largely emit blue light contain newly forming massive blue stars and are thereby star-forming. Galaxies separated by colour tend to occupy different environments, where red galaxies are found in very dense clustered environments and blue galaxies are generally not. Consequently, environment must play some role in the truncation of star formation in galaxies. To understand the nature of this connection, in this work I measure the clustering properties of galaxies as a function of their physical properties. Using H"180deg2 of the Galaxy And Mass Assembly (GAMA) survey, I measure the projected clustering and dark matter halo occupation statistics for 172,377 galaxies as a function of rest-frame r-band luminosity, stellar mass and colour, over the redshift (z) range 0.05 z 0.4. This clustering analysis is then extended over the redshift range 0.2