Disc galaxy modelling with a particle-by-particle M2M method
  We have developed the initial version of a new particle-by-particle
adaptation of the made-to-measure (M2M) method, aiming to model the Galactic
disc from upcoming Galactic stellar survey data. In our new
particle-by-particle M2M, the observables of the target system are compared
with those of the model galaxy at the position of the target stars (i.e.
particles). The weights of the model particles are changed to reproduce the
observables of the target system, and the gravitational potential is
automatically adjusted by the changing weights of the particles. This paper
demonstrates, as the initial work, that the particle-by-particle M2M can
recreate a target disc system created by an N-body simulation in a known dark
matter potential, with no error in the observables. The radial profiles of the
surface density, velocity dispersion in the radial and perpendicular
directions, and the rotational velocity of the target disc are all well
reproduced from the initial disc model, whose scale length is different from
that of the target disc. We also demonstrate that our M2M can be applied to an
incomplete data set and recreate the target disc reasonably well when the
observables are restricted to a part of the disc. We discuss our calibration of
the model parameters and the importance of regularization.
