The unmixed debris of gaia-sausage/enceladus in the form of a pair of halo stellar overdensities
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2022
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In the first billion years after its formation, the Galaxy underwent several mergers with dwarf satellites of various
masses. The debris of Gaia-Sausage/Enceladus (GSE), the galaxy responsible for the last significant merger of the
Milky Way, dominates the inner halo and has been suggested to be the progenitor of both the Hercules-Aquila
Cloud (HAC) and Virgo Overdensity (VOD). We combine SEGUE, APOGEE, Gaia, and StarHorse distances
to characterize the chemodynamical properties and verify the link between HAC, VOD, and GSE. We find that the
orbital eccentricity distributions of the stellar overdensities and GSE are comparable. We also find that they have
similar, strongly peaked, metallicity distribution functions, reinforcing the hypothesis of common origin.
Furthermore, we show that HAC and VOD are indistinguishable from the prototypical GSE population within all
chemical-abundance spaces analyzed. All these evidences combined provide a clear demonstration that the GSE
merger is the main progenitor of the stellar populations found within these halo overdensities.
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PEROTTONI, Hélio D. et al. The unmixed debris of gaia-sausage/enceladus in the form of a pair of halo stellar overdensities. Astrophysical Journal Letters, Bristol, v. 936, n. 1, e7, 2022. DOI: 10.3847/2041-8213/ac88d6. Disponível em: https://iopscience.iop.org/article/10.3847/2041-8213/ac88d6. Acesso em: 11 maio 2023.