Speaker
Description
Recent advances in simulations and observations of galaxy clusters suggest the existence of a physical outer boundary for massive cluster-sized dark matter (DM) halos. Large-scale structures, including halo and cosmic-web boundaries, significantly influence splashback and shock phenomena. Using the Omega500 zoom-in hydrodynamical cosmological simulations, we found that the accretion shock radius is offset from the DM splashback radius, challenging predictions of self-similar models. Specifically, the accretion shock radius exceeds all definitions of the splashback radius in the literature by 20−100%. Identified by the steepest drop in entropy and pressure profiles, the accretion shock radius is roughly twice as large as the splashback radius defined by the steepest slope in the DM density profile and about 1.2 times larger than the edge of the DM phase space structure.
In this talk, we examine how large-scale structures influence the shock and splashback radii of DM halos and the roles of halo boundaries and cosmic-web structures in accretion shock phenomena. We explore the relationship between the gas accretion shock and splashback radius, highlighting challenges in defining these locations. We discuss the aspherical distributions of gas and DM, the critical roles of penetrating filaments, and the need to move beyond spherical assumptions in halo models. Our roadmap for improving these models, such as incorporating a halo+filament model, aims to better represent cosmic structures. This is crucial for understanding galaxy evolution and quenching mechanisms and interpreting recent SZ profile measurements while exploring prospects for measuring the shock radius.
