Origin of the Radcliffe wave in the Milky Way Galaxy
Phys. Rev. D 114, 023017 – Published 13 July, 2026
DOI: https://doi.org/10.1103/7dwy-j47d
Abstract
The origin of a 2.7-kpc-long, narrowly stretched in the plane, vertically sinusoidal, and kinematically coherent complex of dense gas clouds and star-forming regions in the Milky Way Galaxy’s disk near the Sun—the “Radcliffe wave” (RW)”—remains unclear. Analogous large-scale waves, containing young stars that weave above and below the galactic disk, also known as vertical corrugations, have been observed in the stellar disks of nearby rotation-flattened giant galaxies, as well as in the Galaxy. To resolve the issue, we consider a self-gravitating differentially rotating stellar disk of the Galaxy, allowing for noncircular motion of stars. A dispersion relation is derived to describe the collective dynamics of spontaneous bending gravity perturbations developing in the disk by exploring a linear kinetic theory based on the self-consistent system of the Vlasov and Poisson equations. These odd-to-the-mean plane perturbations compress/disperse the medium in spirals perpendicular to its plane and propagate horizontally, making the disk rippled. The self-excitation of oscillatory growing spiral bending waves via the wave-star resonant interaction is proposed to be responsible for the vertically short , still radially long wavelength RW rippling outward to the outer parts of the disk. Self-gravity effects are essential for the formation of waves. This is a collisionless phenomenon that relies solely on the kinetic energy exchange between stars and waves; the regular circular rotation represents a free energy source that the stars will decrease as instability develops. It resembles an inverse Landau damping, so a fluid-dynamics description cannot be used to disclose the phenomenon because, in this case, the equations of a theory lose microstructure.
