Normalized cumulative gas mass versus cooling time for the objects in our sample. For each object we plot the distributions for p = −2, −100, 1 (α = 0.5, 0.99, 2) and shade the region between them. The gas mass is normalized to the total gas mass. For comparison we show, as small filled circles following the same color coding of the gas mass distributions, the values of the cooling time obtained from a single temperature analysis of our spectra. The gray vertical box corresponds to t_cool = (3 − 3.3) Gyr. Note that only CC objects have mass distributions extending below this value.