From ridges in the velocity distribution to wiggles in the rotation
  curve
  Recently, the Gaia data release 2 (DR2) showed us the richness in the
kinematics of the Milky Way disk. Of particular interest is the presence of
ridges covering the stellar velocity distribution, $V_{\phi}-R$; as shown by
others, it is likely that these ridges are the signature of phase mixing,
transient spirals, or the bar. Here, with a Galactic model containing both: bar
and spirals, we found the same pattern of ridges extending from the inner to
the outer disk. Interestingly, ridges in the $V_{\phi}-R$ plane correlate
extremely well with wiggles in the computed rotation curve (RC). Hence,
although the DR2 reveals (for the first time) such substructures in a wide
spatial coverage, we notice that we have always seen such pattern of ridges,
but projected into the form of wiggles in the RC. The separation and amplitude
of the wiggles strongly depend on the extension and layout of ridges in the
$V_{\phi}-R$ plane. This means that within the RC are encoded the kinematic
state of the disk as well as information about the bar and spiral arms. The
amplitude of the wiggles suggests that similar features currently observable in
external galaxies RCs have similar origins, triggered by spirals and bars.
