Cluster outskirts and their connection to the cosmic web

Abstract: We review the latest developments in our X-ray observational and theoretical understanding of the outskirts of galaxy clusters, and their connection to the cosmic web. The faint cluster outskirts are challenging regions to observe in X-rays, requiring highly sensitive telescopes with low and stable background levels. We present our latest understanding of the thermodynamic profiles of clusters in the outskirts, and the biases that gas clumping and non-thermal pressure support can introduce. Features in the outskirts due to merging activity are discussed, along with the chemical enrichment of the outskirts ICM. We describe future prospects for X-ray observations to explore further out in the cluster outskirts and probe their connections to the cosmic web.