Diagnostics used to confirm that the remnant of model gSagSao23 is fully merged and structurally relaxed (Sect. 3.2). We represent the radial profiles of the accumulated mass contained within each radius (middle panel) and volume density (bottom panel) of the old stellar material of progenitor 2 in the final remnant of the model. We compare the profiles for the initial and final times of the simulations (red triangles and black squares, respectively), centred in its own mass distribution at t₀ = 0 and in the mass centroid of progenitor 1 in the final time, t_f. The radii enclosing different percentages of the old stellar mass of progenitor 2 are marked in the top panel for each time (dotted and dashed vertical lines, respectively). The final profiles of both physical quantities indicate that the stellar content of progenitor 2 is well mixed with that of progenitor 1 in the final remnant. Moreover, the final distance between the centroids of the stellar material of each progenitor, D_c, is lower than the softening length of the simulations at the final time (see the bottom panel). This remnant is an elliptical, according to its morphology in its mock V-band images (top panels).