Relation between the core-excised X-ray luminosity L_Xc and mass estimated from the Y_X proxy, for the bolometric and soft-band luminosities of 118 systems. Left: best fitting relation (grey envelope) to the full sample (data points) with the evolution factor n left free to vary. The best-fitting values of n are given in Table 2. Right: histogram of the log space residuals from the best fitting relation. Solid lines show the best-fitting Gaussian distributions with σ corresponding to the best-fitting intrinsic scatter in log space (Table 2).