Origin of the Galactic v wave

Determine the physical mechanism that generated the oscillatory mean radial-velocity pattern as a function of angular momentum J_phi (the v wave) observed in Milky Way disk stars within the Gaia data, identifying the responsible perturbation(s) and their properties.

Background

The paper studies the oscillatory signal in mean radial velocity versus angular momentum (the v wave) revealed by Gaia, develops a linear perturbation-theory framework, and compares several candidate perturbers (impulsive tidal kicks, a rotating bar, and transient spirals). While the analytic model and test-particle simulations suggest a transient spiral can reproduce key features of the signal, the fundamental cause of the observed wave is not established in the abstract.

Pinning down the responsible dynamical event (e.g., bar/spiral activity, tidal interaction) and its parameters remains central to interpreting the Galaxy’s recent dynamical history and testing models of disk disequilibrium.