Stirred, not shaken: Dislodging ω Centauri from the Sausage galaxy through bar resonances
Abstract
We test the idea proposed by Laporte \& Orkney that ω Centauri (ωCen) 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 Ωb=39±3.5 km s−1 kpc−1 and rate of slow-down Ω̇b= 4.5 ± 1.4 km s−1 kpc−1 Gyr−1 to study how bar resonances modulate the angular momentum and energies of both GSE-debris and ωCen's location in (E,Lz) space. We find that the retrograde 3:2 resonance is capable of inflicting changes of ΔE≈0.4×105 km2 s−2, ΔLz≈0.3−0.5×103 km s−1 kpc−1 within timescales of Δt≈ 0.5−1 Gyr, well within the bar's lifespan tbar≈10−8 Gyr. These results are independent of the choice of potential or modelling. We uncover a sample of N-rich stars with metallicities −2.0<[Fe/H]<−1.0 and aluminium enrichments consistent with ωCen. In (E,Lz) space, the map reveals a corridor of trailing N-rich stars clustered about the region connecting ωCen to the GSE's debris centroid, matching ωCen's past predicted track. This provides the best evidence yet that ωCen is the nuclear star cluster of the GSE. Using M54 and ωCen'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.
Related
- Bar-induced migration of ω Centauri away from Gaia Sausage-Enceladus
- The pulsar population of Omega Centauri: New TRAPUM searches, timing, and cluster dynamics with MeerKAT and Parkes
- Multiwavelength Classification of Chandra Sources in Omega Centauri
- VINTERGATAN-GM: Long-lived satellite planes induced by a massive Gaia-Sausage-Enceladus-like merger
- Proxima Centauri's Angular Diameter Revisited
BibTeX
@misc{mannu2026stirred,
title = {{Stirred, not shaken: Dislodging $ω$ Centauri from the Sausage galaxy through bar resonances}},
author = {Axel Mannu and Chervin F. P. Laporte and Matthew D. A. Orkney and Yassin Rany Khalil and Benoit Famaey},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.07581},
eprint = {2610.07581},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.07581},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Stirred, not shaken: Dislodging ω Centauri from the Sausage galaxy through bar resonances
AU - Axel Mannu
AU - Chervin F. P. Laporte
AU - Matthew D. A. Orkney
AU - Yassin Rany Khalil
AU - Benoit Famaey
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2610.07581
UR - https://arxiv.org/abs/2610.07581
AB - We test the idea proposed by Laporte \& Orkney that ω Centauri (ωCen) 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±3.5 km s^−1 kpc^−1 and rate of slow-down Ω̇_b= 4.5 ± 1.4 km s^−1 kpc^−1 Gyr^−1 to study how bar resonances modulate the angular momentum and energies of both GSE-debris and ωCen's location in (E,L_z) space. We find that the retrograde 3:2 resonance is capable of inflicting changes of ΔE≈0.4×10^5 km^2 s^−2, ΔL_z≈0.3−0.5×10^3 km s^−1 kpc^−1 within timescales of Δt≈ 0.5−1 Gyr, well within the bar's lifespan t_bar≈10−8 Gyr. These results are independent of the choice of potential or modelling. We uncover a sample of N-rich stars with metallicities −2.0<[Fe/H]<−1.0 and aluminium enrichments consistent with ωCen. In (E,L_z) space, the map reveals a corridor of trailing N-rich stars clustered about the region connecting ωCen to the GSE's debris centroid, matching ωCen's past predicted track. This provides the best evidence yet that ωCen is the nuclear star cluster of the GSE. Using M54 and ωCen'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.
ER -