Lucey, MadelineHawkins, KeithNess, MelissaDebattista, Victor P.Luna, AliceAsplund, MartinBensby, TCasagrande, LucaFeltzing, SofiaFreeman, KennethKobayashi, ChiakiMarino, Anna F2023-03-292023-03-290035-8711http://hdl.handle.net/1885/287864The metal-poor stars in the bulge are important relics of the Milky Way's formation history, as simulations predict that they are some of the oldest stars in the Galaxy. In order to determine if they are truly ancient stars, we must understand their origins. Currently, it is unclear if the metal-poor stars in the bulge ([Fe/H] < -1 dex) are merely halo interlopers, a unique accreted population, part of the boxy/peanut-shaped bulge, or a classical bulge population. In this work, we use spectra from the VLT/FLAMES spectrograph to obtain metallicity estimates using the Ca-II triplet of 473 bulge stars (187 of which have [Fe/H] < -1 dex), targeted using SkyMapper photometry. We also use Gaia DR2 data to infer the Galactic positions and velocities along with orbital properties for 523 stars. We employ a probabilistic orbit analysis and find that about half of our sample has a >50 per cent probability of being bound to the bulge, and half are halo interlopers. We also see that the occurrence rate of halo interlopers increases steadily with decreasingmetallicity across the full range of our sample (-3<[Fe/H]< 0.5). Our examination of the kinematics of the confined compared to the unbound stars indicates themetal-poor bulge comprises at least two populations; those confined to the boxy/peanut bulge and halo stars passing through the inner galaxy. We conclude that an orbital analysis approach, as we have employed, is important to understand the composite nature of the metal-poor stars in the inner region.KH has been partially supported by a TDA/Scialog (2018-2020) grant funded by the Research Corporation and a TDA/Scialog grant (2019-2021) funded by the Heising-Simons Foundation. KH and ML acknowledges support from the National Science Foundation grant AST-1907417 and from the Wootton Center for Astrophysical Plasma Properties funded under the United States Department of Energy collaborative agreement DE-NA0003843. VPD is supported by Science and Technology Facility Council (STFC) Consolidated grant # ST/R000786/1. TB acknowledges financial support by grant No. 2018-04857 from the Swedish Research Council. LC is the recipient of an Australian Research Council (ARC) Future Fellowship (project number FT160100402). C.K. acknowledges funding from the UK Science and Technology Facility Council (STFC) through grant ST/ R000905/1. AFM acknowledges support from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie (Grant Agreement No 797100). The simulation used in this paper was run at the High Performance Computing Facility of the University of Central Lancashireapplication/pdfen-AU© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Societystars: kinematics and dynamicsstars: Population IIGalaxy: bulgeGalaxy: evolution202110.1093/mnras/stab0032022-01-16