Vertical velocity patterns in the Milky Way disc: RAVE-Gaia streaming motions

Abstract

Using data from the Radial Velocity Experiment (RAVE) and the Tycho- Gaia astrometric solution catalogue (TGAS), we study the vertical velocity (Vz) patterns in the Milky Way disc. We search in particular for variation in velocity with distance above and below the disc midplane. In contrast to previous suggestions of a breathing mode seen in RAVE data, our results support a combination of bending and breathing modes, likely generated by a combination of external or internal and external mechanisms.