Can we really pick and choose? Benchmarking various selections of Gaia Enceladus/Sausage stars in observations with simulations

Understand

Large spectroscopic surveys plus Gaia astrometry have shown us that the inner stellar halo of the Galaxy is dominated by the debris of Gaia Enceladus/Sausage (GES).

• With the richness of data at hand, there are a myriad of ways these accreted stars have been selected.
• We investigate these GES selections and their effects on the inferred progenitor properties using data constructed from APOGEE and Gaia.
• We explore selections made in eccentricity, energy-angular momentum (E-Lz), radial action-angular momentum (Jr-Lz), action diamond, and [Mg/Mn]-[Al/Fe] in the observations, selecting between 144 and 1,279 GES stars with varying contamination from in-situ and other accreted stars.