Evidence of a vertical kinematic oscillation beyond the Radcliffe Wave
  The Radcliffe Wave (RW) is a recently discovered sinusoidal vertical feature
of dense gas in the proximity of the Sun. In the disk plane, it is aligned with
the Local Arm. However, the origin of its vertical undulation is still unknown.
This study constrains the kinematics of the RW, using young stars and open
clusters as tracers, and explores the possibility of this oscillation being
part of a more extended vertical mode. We study the median vertical velocity
trends of the young stars and clusters along with the RW and extend it further
to the region beyond it. We discover a kinematic wave in the Galaxy, distinct
from the warp, with the amplitude of oscillation depending on the age of the
stellar population. We perform a similar analysis in the N-body simulation of a
satellite as massive as the Sagittarius dwarf galaxy impacting the galactic
disk. When projected in the plane, the spiral density wave induced by the
satellite impact is aligned with the RW, suggesting that both may be the
response of the disk to an external perturbation. However, the observed
kinematic wave is misaligned. It appears as a kinematic wave travelling
radially, winding up faster than the density wave matched by the RW,
questioning its origin. If a satellite galaxy is responsible for this kinematic
wave, we predict the existence of a vertical velocity dipole that should form
across the disk and this may be measurable with the upcoming Gaia DR3 and DR4.
