CLASH Lensing View of the Formation and Evolution of Galaxy Clusters
I will talk about the recent discovery (Fujita, Umetsu, Rasia, Meneghetti, Donahue, Medezinski, Okabe, & Postman ) of a universal "plane" dictating dark-matter halo evolution from our gravitational lensing and X-ray observations from the CLASH survey. We show that high-mass galaxy clusters lie on a plane in the three-dimensional logarithmic space of their characteristic halo radius "rs", mass "Ms" , and X-ray temperature "Tx" with a very small orthogonal scatter. The tight correlation indicates that the gas temperature was determined at a specific cluster formation time, which is encoded in (rs,Ms) and that the gas was heated when the clusters were in the fast-growing phase. Intriguingly, the plane is significantly tilted with respect to the canonical virial expectation, Tx ~ Ms /rs. We show that the self-similar solution of Bertschinger (1985) for secondary infall and accretion can explain the observed relation, Tx ~ Ms^1.5 /rs^2. Numerical simulations reproduce the observed plane and its angle. This result holds independently of the gas physics implemented in the code, revealing the fundamental origin of this plane.