The stellar kinematics of co-rotating spiral arms in Gaia mock
  observations
  We have observed an N-body/Smoothed Particle Hydrodynamics simulation of a
Milky Way like barred spiral galaxy. We present a simple method that samples
N-body model particles into mock Gaia stellar observations and takes into
account stellar populations, dust extinction and Gaia's science performance
estimates. We examine the kinematics around a nearby spiral arm at a similar
position to the Perseus arm at three lines of sight in the disc plane;
(l,b)=(90,0), (120,0) and (150,0) degrees. We find that the structure of the
peculiar kinematics around the co-rotating spiral arm, which is found in Kawata
et al. (2014b), is still visible in the observational data expected to be
produced by Gaia despite the dust extinction and expected observational errors
of Gaia. These observable kinematic signatures will enable testing whether the
Perseus arm of the Milky Way is similar to the co-rotating spiral arms commonly
seen in N-body simulations.
