2024MNRAS.52711393H

The second data release of ESA's Gaia mission revealed numerous signatures of disequilibrium in the Milky Way's disc. These signatures are seen in the planar kinematics of stars, which manifest as ridges and ripples in R-v_ϕ, and in vertical kinematics, where a prominent spiral is seen in the z-v_z phase space. In this work, we show an equivalent ΔR-v_R phase spiral forms following a perturbation to the disc. We demonstrate the behaviour of the ΔR-v_R phase spirals in both a toy model and a high-resolution N-body simulation of a satellite interaction. We then confront these models with the data, where we find partial ΔR-v_R phase spirals in the Solar neighbourhood using the most recent data from Gaia DR3. This structure indicates ongoing radial phase mixing in the Galactic disc, suggesting a history of recent perturbations, either through internal or external (e.g. satellite) processes. Future work modelling the z-v_z and ΔR-v_R phase spirals in tandem may help break degeneracy's between possible origins of the perturbation.