Chemodynamical signatures of bar resonances in the Galactic disk: current data and future prospects

The Galactic disk exhibits complex chemical and dynamical substructure thought to be induced by the the bar, spiral arms, and satellites. Here, we explore the chemical signatures of bar resonances in action and velocity space and characterize the differences between the signatures of corotation and higher-order resonances using test particle simulations. Thanks to recent surveys, we now have large homogeneous datasets containing metallicities and kinematics of stars outside the solar neighborhood. We compare the simulations to the observational data from Gaia EDR3 and LAMOST DR5, and find weak evidence for a slow bar that associates the "hat" moving group with its outer Lindblad resonance and "Hercules" with corotation. While constraints from current data are limited by their spatial footprint, stars closer in azimuth than the Sun to the bar's minor axis show much stronger chemodynamical signatures of the bar's outer Lindblad and corotation resonances in test particle simulations. Future datasets with greater azimuthal coverage, including the final Gaia data release, will allow reliable chemodynamical identification of bar resonances.