Astronomy Tea Talk

Galaxy cluster growth is expected to proceed inside-out with the core being assembled at early times and the outskirts still in the accretion phase today. Unfortunately, the determination of the thermodynamic properties of the intracluster outskirts is challenging at best. In this seminar, I will present the thermodynamic profiles of a z=0.1 cluster, Abell 2224, till the virial radius. We found a flattening of the entropy profile that witnesses the theoretically-predicted decrease in the inflow through the virial boundary. The bending is robustly determined by Swift X-ray data alone, by using Planck data, and also by the combination of observables with different sensitivities to systematics.