Spatial Property of Multiple Metallic Populations in the Tidal Stream of <i>ω</i> Centauri

Abstract ω Centauri, the remnant nucleus of an accreted dwarf galaxy, is a unique laboratory for studying complex stellar populations. The recently discovered Fimbulthul stream provides a fossil record of its ongoing tidal dissolution. In this work, we investigate the spatial distributions of metal-rich and metal-poor populations within ω Centauri and its stream to constrain the cluster’s formation history. Using synthetic photometry from Gaia DR3 XP spectra, we classify stars via a support vector classifier. The spatial distributions are then compared to a scaling N -body simulation performed with the PeTar code. Our analysis reveals no significant radial gradient in population ratios within the cluster, though the metal-rich stars may be slightly more extended. The population ratio in the tidal stream is consistent with that of the present-day cluster, albeit with large uncertainties. Our simulation indicates that any initial radial gradient must have been shallow, with a maximum fraction difference less than 0.15. Both observational and dynamical results suggest that the metal-rich population is not formed in a centrally concentrated manner. By combining our results and existing literature, we propose a new formation scenario for ω Centauri.