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The Spiderweb galaxy (aka PKS1138-262) so called as this Hubble Space Telescope image gives it the appearance of flies being caught in its gravitational web. This proto-cluster is forming at just 3.5 billion years after the Big Bang and was discovered via its powerful radio emission (seen from the red contours). This project aims to use polarised radio observations to probe the intra-cluster medium in this system and possibly others. Picture credit: George Miley

The Spiderweb galaxy (aka PKS1138-262) so called as this Hubble Space Telescope image gives it the appearance of flies being caught in its gravitational web. This proto-cluster is forming at just 3.5 billion years after the Big Bang and was discovered via its powerful radio emission (seen from the red contours). This project aims to use polarised radio observations to probe the intra-cluster medium in this system and possibly others. Picture credit: George Miley

Clusters are the most massive bound structures in the Universe and are a unique place to study galaxy formation. Around half of the stellar mass of the Universe is produced in clusters or their proto-cluster ancestors. Tracing proto-clusters in the distant Universe is difficult as traditional techniques become much less effective. However, the most powerful radio sources are unique beacons of the earliest over-densities which form proto-clusters. Using radio surveys, we have discovered many high redshift proto-clusters associated with powerful radio galaxies.
This project aims to ‘weigh’ the proto-clusters and possibly determine the distribution of hot intra-cluster medium via the Sunyaev-Zel’dovich (SZ) effect. The SZ effect causes a distortion in the Cosmic Microwave Background (CMB) due to the hot thermal electrons in the cluster gravitational potential well scattering the CMB photons. The strength of this effect is directly proportional to the mass of hot intra-cluster medium, which dominates the non-dark matter mass of clusters, hence providing a more robust measure of their total mass.
This project will take advantage of deep high frequency radio observations from both the Australian Telescope Compact Array and the Atacama Large Millimetre Array to search for this effect. Detections of the SZ effect in the distant Universe is rare. Much of this data is in hand from projects with other scientific goals, so the goal of this project would be to determine the feasibility of this technique with the data we have on sources like the Spiderweb (below). If successful we would apply for further time to follow-up other prime high redshift proto-clusters.

Co-Supervisor

Dr Guillaume Drouart

Research Associate

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