Left panel: Similar to Figure 1, but for the density distribution of all the gas particles for GIZMO-SIMBA (colour-filled contours) and GADGET-X (contours). The contour lines enclose 20%, 50%, 80%, 95%, and 99% of gas particles within the analysis region, with 2D radii normalised to R_200c. The two black contours indicate the region on this plane that encloses 50% of the WHIM gas in each simulation. Right panel: Radial profile of the fraction of gas that is WHIM. Coloured lines show different halo mass removal thresholds as indicated in the legend.