Logarithm of the IGL mass (a)–(b) and IGL fraction (c)–(d) plotted, respectively, against the Δℳ₂₋₁> and Δℳ₃₋₁> magnitude gaps of the BGG. (e) IGL fraction vs. the logarithm of the IGL mass. In panels (a)–(e) blue stars represent single-BGG groups (for which Δℳ₂₋₁> ≥ 0.75 mag), orange diamonds double-BGG groups (Δℳ₂₋₁> ≤ 0.5 mag and Δℳ₃₋₂> ≥ 0.75 mag), and green circles non-BGG groups (both Δℳ₂₋₁> and Δℳ₃₋₂> are less than 0.75 mag, indicating the absence of a clearly dominant BGG). The solid lines and shaded bands in these panels illustrate, following the same colour scheme, linear fits and their associated uncertainties for each BGG subset. The fits are included to highlight the moderately strong positive linear correlation (Pearson coefficients r = 0.46 and r = 0.49, respectively) that exists between f_IGL and Δℳ₂₋₁> and Δℳ₃₋₁> for the single-BGG group subset (panels c and d), as well as the mild positive relationship (r = 0.33) observed between f_IGL and Δℳ₃₋₁> for the double-BGG group subset (panel d). Since the magnitude gaps are view-independent, data in all these panels are limited to single-axis projections of the z = 0 snapshots for the sake of clarity, showing only measurements in the XY plane. (f) Same as Fig. 5, but for the IGL fraction at z = 0. In this case, the probabilities are derived from the 300 measurements of f_IGL obtained using the three orthogonal projections.