Abstract
We present our work producing Milky Way Halo mock Gaia catalogues and using nGC3, a great-circle cell counts method, to search for tidal streams using positional information and proper motions. Our ten Galactic Halo mock catalogues were made from Milky-Way-mass haloes from the Aquarius and HYDRO-zoom cosmological simulations, and reproduce the Gaia selection function and observational errors for two stellar tracers: K giants and RR Lyrae stars. The diversity of orbits and progenitors in the simulations allow us to characterize the nGC3 methods completeness and detection limits in a realistic setting. We show the nGC3 method has a well-defined detection boundary, whose location can be predicted based on direct observables alone. We expect a total of 4-13 tidal streams produced by dwarf galaxies to be detectable with Gaia+nGC3 with K giant and RR Lyrae stars combined, and estimate a detection efficiency >80% inside the boundary. Successfully recovered progenitors are in the mass range of classical Milky Way dwarf satellites, with stellar masses down to ∼106M⊙, and may have been accreted as early as z≲3.
