2D phase plots showing the volume-weighted distribution of gas number density n vs temperature T within the central 60 kpc of the cluster for a stacked sample measured every 0.25 Myr between t = 0 Gyr and t = 3 Gyr. Solid (dashed) grey lines show example lines along which gas evolves when it cools in an isobaric (isochoric) fashion. Histograms along the x-axis (y-axis) show 1D histograms for the number density (temperature), weighted by V/V_tot, where V_tot is the total volume probed here. Solid lines show the distribution at individual points in time, and the dashed line shows the distribution for the stacked sample. With increasing resolution, the distribution becomes broader, but the generally isochoric nature of cooling remains.