A New Model for the Milky Way Bar

We use Schwarzschild’s orbit-superposition technique to construct self-consistent models of the Galactic bar. Using ${\chi }^2$ minimisation, we find that the best-fit Galactic bar model has a pattern speed $\Omega_{\rm p}=60 \rm{km s^{-1} kpc^{-1}}$,diskmass$\rm{M_{\rm d}=1.0\times10^{11}M_{\odot}}$andbarangle$\theta_{\rm bar}=20^{\circ}$ for an adopted bar mass ${\mathrm{M}}_{\mathrm{b}\mathrm{a}\mathrm{r}}=2\times {10}^{10}{\mathrm{M}}_{\odot }$. 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 $l=[-{12}^{\circ },{12}^{\circ }]$, $b=[-{10}^{\circ },{10}^{\circ }]$, 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.