Three-dimensional thermodynamic profiles of the IGrM of S4436. The left-hand panel shows the electron density profile (blue curve). For comparison, the black curve and shaded area show the mean and scatter of the gas density profiles in a sample of massive galaxy clusters (Ghirardini et al. 2019). The middle panel shows the gas entropy obtained using the parametric (cyan curve) and non-parametric (blue points) deprojection techniques, compared with the entropy profile expected from gravitational collapse (Voit et al. 2005) (dashed curve) and with the entropy profiles of galaxy groups in the same mass range (Sun et al. 2009) (orange curve and shaded area). The right-hand panel shows the reconstruction of the gas cooling time, with the approximate age of the Universe, 1/H₀, indicated by the horizontal dashed line. In all three panels, the vertical dashed line shows the location of R₅₀₀ = 648 kpc.