Tidal Debris Candidates from the ω Centauri Accretion Event and Its Role Building Up the Milky Way Halo

Anguiano, Borja; Mitschang, Arik W.; Kirihara, Takanobu; Hirai, Yutaka; Horta, Danny; Hasselquist, Sten; Schiavon, Ricardo P.; Majewski, Steven R.; Mason, Andrew C.; Price-Whelan, Adrian M.; Allende Prieto, Carlos; Smith, Verne V.; Cunha, Katia; Nidever, David L.
Bibliographical reference

The Astrophysical Journal

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8
2025
Number of authors
14
IAC number of authors
1
Citations
2
Refereed citations
0
Description
We identify stellar tidal debris from the ω Centauri (ω Cen) system among field stars in the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey via chemical tagging using a neural network trained on APOGEE observations of the ω Cen core. We find a total of 463 ω Cen debris candidates have a probability P > 0.8 of sharing common patterns in their chemical abundances across a range of individual elements or element combinations, including [C+N], O, Mg, Al, Si, Ca, Ni, and Fe. Some debris candidates show prograde or retrograde disk-like kinematics, but most show kinematics consistent with the accreted halo, showing high radial actions, JR, values. We find that a sample of Gaia-Sausage-Enceladus (GES) members are chemically distinct from the ω Cen core, suggesting that ω Cen is associated with an independent merger event shaping the Milky Way halo. However, a connection between GSE and ω Cen cannot be ruled out. A detailed comparison with N-body simulations indicates that the ω Cen progenitor was a massive dwarf galaxy (≳108M⊙). The existence of a metal-poor high-α chemically homogeneous halo debris is also reported.
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Chemical Abundances in Stars
Stellar spectroscopy allows us to determine the properties and chemical compositions of stars. From this information for stars of different ages in the Milky Way, it is possible to reconstruct the chemical evolution of the Galaxy, as well as the origin of the elements heavier than boron, created mainly in stellar interiors. It is also possible to
Carlos
Allende Prieto