Omega Centauri (omega Cen) stands as a unique anomaly in the Milky Way, a stellar system of extreme mass and chemical complexity widely considered the relic nucleus of an accreted dwarf galaxy. However, the full extent of its progenitor’s debris has remained a subject of intense debate. In this presentation, I will demonstrate our hypothesis of a unified progenitor: the omega Dwarf. Utilising high-resolution spectroscopic abundances from the APOGEE and GALAH surveys in tandem with Gaia DR3 astrometry, we reconstruct the multi-dimensional chemical space of the omega Dwarf stellar populations and, in combination with orbital energy, perform a chemical stratigraphy across the dwarf galaxy. Our findings reveal a clear spatial-chemical segregation: chemically evolved populations, characterised by enrichments in Aluminium (Al), Nitrogen (N), and Helium (He), are tightly confined to the deepest potential wells, suggesting a secondary, high-density star-formation burst during the merger. The metallicity profile exhibits an inverted U-shape, a hallmark of present-day nucleated dwarf galaxies where central gas inflows drive late-stage enrichment. Furthermore, the inner region shows a marked alpha-enhancement compared to the outskirts, indicating a shorter, more efficient star-formation timescale likely fueled by the rapid migration of inspiraling globular clusters. Ultimately, our results demonstrate that the omega Dwarf is a major contributor to the assembly of the Milky Way’s halo and confirm omega Cen as its final, resilient survivor.
