Stirred, not shaken: Dislodging omega Centauri from the Sausage galaxy through bar resonances

We test the idea proposed by Laporte & Orkney that ω Centauri (ω Cen) is the central nuclear star cluster of the Gaia-Sausage-Enceladus galaxy (GSE) which got dislodged by the bar. We run a series of simulations in time-evolving bar potentials with present-day pattern speeds within Portail et al's Ω b=39 plus or minus3.5, and rate of slow-down Ω b= 4.5 plus or minus 1.4, to study how bar resonances modulate the angular momentum and energies of both GSE-debris and ω Cen's location in (E,L z) space. We find that the retrograde 3:2 resonance is capable of inflicting changes of ΔE about0.4 times10 5,, ΔL z about0.3-0.5 times10 cubed, within timescales of Δt about 0.5-1,, well within the bar's lifespan t about10-8,. These results are independent of the choice of potential or modelling. We uncover a sample of N-rich stars with metallicities-2.0<[]<-1.0 and aluminium enrichments consistent with ω Cen. In (E,L z) space, the map reveals a corridor of trailing N-rich stars clustered about the region connecting ω Cen to the GSE's debris centroid, matching ω Cen's past predicted track. This provides the best evidence yet that ω Cen is the nuclear star cluster of the GSE. Using M54 and ω Cen's chemistry we show that neither first nor second generations follow general galaxy-wide scale chemical enrichment trends. This is empirical evidence that GC chemical trends are a cluster-scale physics problem, not a galaxy-wide one.