The multiple corrugations in the Galactic disk derived from the LAMOST and Gaia survey data

Context . Large spectroscopic and astrometric surveys have revealed complex wave-like features in the Milky Way disk, suggesting that its kinematic and chemical structures are shaped by time-dependent perturbations. Recent studies have reported oscillatory patterns in the R g – V ϕ − V R space, hinting at a possible structural transition in the outer disk. Aims . We aim to characterise the transition between the inner and outer Galactic thin disk and to investigate whether radial corrugations can provide a plausible physical interpretation of the observed features. Methods . We analysed two large stellar samples from LAMOST DR8 and Gaia DR3, combining spatial, kinematic, and chemical diagnostics. A simplified corrugation model – consisting of two radial waves propagating in opposite directions – was constructed and fitted to the observed V R pattern. We further validated the model using N -body simulations. Results . Both LAMOST and Gaia samples reproduce the previously reported wave-like pattern in the R g – V ϕ − V R plane. We identify a clear transition between the inner and outer disks via the variations in rotational velocity and metallicities. The corrugation model naturally reproduces the periodic variation of V R with galactocentric radius, and the superposition of the inward- and outward-propagating modes gives rise to a comparable oscillatory pattern in both observations and simulations. Conclusions . Our modelling suggests that radial corrugations can provide a plausible interpretation of the observed kinematic signatures. The results highlight the complex, multi-perturber nature of the Galactic disk and motivate further investigation with upcoming surveys.