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

Anguiano, B, Mitschang, AW, Kirihara, T, Hirai, Y, Horta, D, Hasselquist, S, Piorno Schiavon, R ORCID: 0000-0002-2244-0897, Majewski, SR, Mason, AC, Price-Whelan, AM, Prieto, CA, Smith, VV, Cunha, K and Nidever, DL (2025) Tidal Debris Candidates from the ω Centauri Accretion Event and Its Role Building Up the Milky Way Halo. The Astrophysical Journal, 989 (1).

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Abstract

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 (≳108 M⊙). The existence of a metal-poor high-α chemically homogeneous halo debris is also reported.

Item Type:	Article
Uncontrolled Keywords:	0201 Astronomical and Space Sciences; 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics; 0306 Physical Chemistry (incl. Structural); Astronomy & Astrophysics; 5101 Astronomical sciences; 5107 Particle and high energy physics; 5109 Space sciences
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society
Date of acceptance:	12 May 2025
Date of first compliant Open Access:	4 August 2025
Date Deposited:	04 Aug 2025 08:48
Last Modified:	04 Aug 2025 09:00
DOI or ID number:	10.3847/1538-4357/adda2c
URI:	https://researchonline.ljmu.ac.uk/id/eprint/26889

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