Searching for the shadows of proto-clusters in the early Universe

Galaxy proto-clusters are the distant progenitors of local galaxy clusters. At redshift z > 2 they are large, diffuse structures, consisting of many dark matter haloes. Observations of these galaxy proto-clusters provide some of the most direct tests of galaxy and cluster formation. They are excellent laboratories in which to study feedback from supermassive black holes, and the formation of the most massive galaxies in the Universe. However, detecting these objects in the first place is a huge challenge. This project will investigate a new method to locate and study proto-clusters utilising the vast quantities of hydrogen gas within these large structures. This hydrogen gas is traced by absorption lines in the Lyman-alpha forest - the series of hydrogen absorption lines observable in the spectra of distant quasars. These absorption lines provide a unique window into the physical properties of proto-clusters in the early Universe. This project will use observations of Lyman-alpha absorption lines in quasar spectra to detect the cool intra-protocluster gas at high redshift. State-of-the-art hydrodynamical simulations (www.nottingham.ac.uk/astronomy/sherwood/) will be used in combination with the observational data to determine the properties of proto-clusters, and to further develop techniques suitable for blind searches for proto-clusters using quasar survey data.