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The normal matter, or baryons, in the nearby Universe are distributed as cold gas, stars, dust and hot plasma, and located in many environments including galaxy halos, the intra-group medium, in filaments, and in voids. Most of this mass has yet to be accurately detected, and hence we have the long-standing “missing baryon problem”. In this project we will use a new and novel method applied to new X-ray and radio facilities, to measure each type of mass within each type of structure.


The project uses the latest redshift catalogue of 250,000 galaxies constructed at UWA, and we will use this catalogue to “stack” the X-ray and radio signals from the eROSITA satellite, and the ASKAP radio array. By “stacking” the signal from the known locations of 1000s of galaxies, groups, filaments and voids we expect to tease out the weak signals to make the very first measurement of the baryon density as a function of environment.


In the later stages we can either extend the project out to higher-redshifts to see how the mass budget evolves, or compare to detailed numerical simulations produced at ICRAR by the simulations team.


The PhD program will train the student in advanced image analysis, statistical analysis, data management, and data visualisation in general, as well as observational cosmology and the interpretation of state-of-the art astronomical data.