Gaia DR3 features of the phase spiral and its possible relation to internal perturbations

ABSTRACT Disc stars from the Gaia DR3 RVS catalogue are selected to explore phase spiral in Galaxy. The data reveal a two-armed pattern local z–vz plane inside solar radius, which appears clearly when colour-coded by 〈vR〉(z, vz): this is characteristic of breathing mode that can principle be produced in-plane non-axisymmetric perturbations. becomes single armed outside radius. When realistic analytic model with steadily rotating bar and 2-armed arms as perturbation used perform particle test integrations, pseudo-stars get prominent 〈vR〉 map x–y plane. Additionally, clear evidence at few $\, \mathrm{km\, s}^{-1}$ level seen 〈vz〉 on x–z plane, confirming such modes non-negligible joint presence arms. However, no perceptible (z, vz) an initial vertical added carry out simulation, one-armed spirals 500 Myr after gradually disappear out. Finally, we show proof concept how toy time-varying varying speed produce strong spiral. We conclude internal together external could perhaps explain transition between around