Region-integrated stellar age–metallicity distributions and their 1D projections. Each column corresponds to a spatial region (whole galaxy, main body, northern clump). The heatmap shows PDF^reg on the native SSP (log t,[Z/H]) grid, defined as the region-summed PPXF template masses normalized to unity (i.e., the fraction of the region’s present-day stellar mass assigned to each template; Appendix B.2). Top panels: star-formation histories derived by converting the mass-weighted distribution to formed mass using the SSP living-mass fraction, marginalizing over metallicity and dividing by the linear time-bin width to yield SFR(t). Side panels: metallicity distribution functions obtained by marginalizing over age and scaling by the region’s present-day stellar mass.