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Astro Seminar

Unveiling structure formation and dark matter properties in the outskirts of galaxy clusters

Speaker: Dominique Eckert (Geneva)
Date: Wednesday 9 December 2020
Time: 14:00
Venue: Zoom

The outer regions of galaxy clusters host the transition between the virialized material of galaxy clusters and the accreting material from the large-scale structure. As such, they are privileged sites to study the formation of massive structures in the Universe. The baryonic content of galaxy clusters is dominated by a hot (~1e8 K), highly ionized plasma, which in galaxy cluster outer regions is difficult to observe directly because of its very low density. I will show that the properties of the intracluster gas at the virial radius can be reconstructed by combining deep X-ray observations with measurements of the Sunyaev-Zeldovich effect. This new technique allowed us to perform a systematic study of the state of the gas out to the virial radius in a sample of systems. I will show how joint X-ray/SZ observations can be used to uncover the processes governing the formation of structures in the Universe. I will also present high-quality reconstructions of the gravitational field of galaxy clusters, which allow us to set constraints on the properties of dark matter and on modified gravity theories. I will discuss the enrichment of the gas in heavy elements and how it can be used to constrain the epoch of metal enrichment. Finally, I will discuss how new and upcoming missions (eROSITA, ATHENA) will advance our knowledge of the physical properties of galaxy clusters.