The cosmic web from eROSITA and galaxy surveys synergy

ongoing

The cosmic web (CW) is a complex network of structures composed of galaxies, dark matter, and gas, formed of galaxy clusters connected by filaments. Low-mass groups and large-scale super-clusters have yet to find a place in the context of the CW. The best way to trace the CW is to use optical galaxy surveys to detect the filaments and X-ray data to detect the hot gas of clusters. The detection of groups and super-clusters requires high-sensitivity X-ray instruments due to the low density of their gas content and has so far been very difficult. The new X-ray telescope eROSITA has however produced X-ray data of unprecedented sensitivity, which allow the discovery of thousands of groups and hundreds of super-clusters. eROSITA opened for the first time the possibility for statistical studies of these structures in the context of the CW. My goal is to exploit the synergy between eROSITA and galaxy surveys to shine new light on the place that groups and super-clusters occupy in the CW. This study will improve our understanding of how filaments channel accretion onto groups and will show how a physical definition for super-clusters (whose definition has so far been empirical) can be achieved in the CW context. The study of the CW is entering a phase of increased interest thanks to recent wide-area galaxy surveys and new X-ray data. Investigations like this project are those that will pave the way for future experiments (e.g. Euclid, ATHENA). This research will provide a significant advancement to our understanding of the CW, structure formation, and galaxy evolution. With this research I will gain deep insight on how to integrate X-ray and optical data in the context of a large collaboration. This project will prepare me to better deal with the outcome expected from future galaxy surveys and X-ray telescopes and will make me more suited to become a group leader at an European institution.