Exploring the impact of a rapidly decelerating bar on transforming bulge orbits into disc-like orbits

Understand

The most metal-poor tail of the Milky Way ([Fe/H] $\leq$ $-$2.5) contains a population of stars with very prograde planar orbits, which is puzzling in both their origin and evolution.

• A possible scenario is that they are shepherded by the bar from the inner Galaxy, where many of the old and low-metallicity stars in the Galaxy are located.
• To investigate this scenario, we use test-particle simulations with an axisymmetric background potential plus a central bar model.
• The test particles are generated by an extended distribution function (EDF) model based on the observational constraints of bulge stars.