Correlation between the different lookback times listed in Table 2 (in units of Gya). The diagonal panels show kernel density estimates of each lookback time distribution, using a Gaussian kernel with σ = 0.1 Gyr, and the median marked by a blue line. The orange and blue curves and dashed vertical lines show distributions and medians for satellites in M_200m > 10¹⁴ M_⊙ and 10¹³ M_⊙ < M_200m < 5 × 10¹³ M_⊙. Each off-diagonal panel in the lower triangle shows the corresponding two-dimensional occupation; the colour scale runs from white (zero) to a colour given by the Spearman correlation coefficient between the two times, shown in the corner of each panel, and coded in the bottom colour bar. The brightness scaling is consistent across panels, with the darkest cells containing 2.5% of the population or more. Each panel in the upper triangle shows the logarithm of the mean subhalo-to-stellar mass ratio at z = 0 in each cell, as coded in the upper colour bar. The numbers in the corners of each panel correspond to the correlation coefficients.