Through a lens darkly: magnified views of massive galaxy formation

At the heart of massive galaxies, there is a supermassive black hole. Astronomers believe that the evolution of galaxies is linked to the growth of their supermassive black holes. To understand this connection, we need to investigate these galaxies in the very distant Universe, during their formation. In my thesis, I investigated the properties of galaxies that contain supermassive black holes that are rapidly consuming matter and producing a huge amount of energy. I used a phenomenon called gravitational lensing, which magnifies these very distant galaxies so they can be seen in better detail. The first half of my thesis were surveys to understand how many stars are forming in these young galaxies. The second half of the thesis focuses on detailed studies at high resolution to measure the size and structure of the galaxies, including their stars and the Hydrogen gas that is available to make new stars. Overall, I found that the galaxies which have rapidly growing supermassive black holes are also very rapidly turning their Hydrogen gas into stars. This is in general agreement with predictions for how these massive galaxies form but provides new information which can be used to improve our understanding of galaxy formation.