Monday

Detecting hot gas in outskirts of galaxy clusters is one of the main goals of our next-generation X-ray and SZ telescopes. It is therefore of importance to understand how accretion and mergers shape the cluster’s atmosphere near and beyond the virial radius. In this talk, I will present our novel approach designed to explore the effects of mergers on the outskirts of clusters, whereby we simulate mergers between two self-similar clusters in an idealized cosmological context. Under this framework, I will discuss the formation and evolution of the “runaway” merger shocks. They are considered as promising candidates for powering radio relics found in many clusters. Eventually, the runaway shocks inevitably overtake the accretion shock. A long-living MA-shock is subsequently formed and constitutes a new boundary of the intracluster medium (ICM) that could travel up to a few virial radii into the intergalactic medium (IGM). In contrast to the gaseous atmosphere, the dark matter (DM) halo experiences a rapid contraction during the major merger and its splashback radius decreases, approaching the virial radius. Our simulations show that mergers could easily generate the MA-shock-splashback offset measured in cosmological simulations. In addition, I will also highlight various shocks and contact discontinuities formed at different epochs of the merger in this talk.