A new model for the Milky Way bar

摘要

We use Schwarzschild's orbit-superposition technique to construct self-consistent models of the Galactic bar. Using χ~2 minimisation, we find that the best-fit Galactic bar model has a pattern speed ?_P = 60 km s~(-1) kpc~(-1), disk mass M_d = 1.0 × 10~(11)M_⊙ and bar angle θ_(bar)= 20° for an adopted bar mass M_(bar) = 2 × 10~(10)M_⊙. The model can reproduce not only the three-dimensional and projected density distributions but also velocity and velocity dispersion data from the BRAVA survey. We also predict the proper motions in the range l = [-12°， 12°]，b = [- 10o, 10o], which appear to be higher than observations in the longitudinal direction. The model is stable within a timescale of 0.5 Gyr, but appears to deviate from steady-state on longer timescales. Our model can be further tested by future observations such as those from GAIA.