Influence of the resonance ring gravity on the stellar velocity distribution near the OLR of the Galactic bar

Abstract

We constructed the 2D model of the Galaxy which initially includes an analytical bar, bulge, disk and halo. The model disk forms the outer elliptical resonance rings R1 and R2 located near the outer Lindblad resonance of the bar (OLR), as well as the inner resonance ring r located near the corotation radius (CR). As the density of stars in the elliptical rings increased, we introduced additional gravitational perturbations created by the rings. The radial component of gravitational perturbations from the elliptical rings, F_R, at a point with the Galactocentric coordinates (R, theta) was represented as a combination of three polynomials in powers R/Re or Re/R, where Re is the distance to the midline (middle) of the ring at a given angle theta. The azimuthal component of the disturbances, F_T, was calculated using the force F_R. The difference between the values of the force F_R (F_T) calculated using the numerical differentiation of the potential and using the analytical representation does not exceed 5.7% (1.3%) of the maximum value of the force F_R generated by the elliptical rings. In general, the gravity of the elliptical rings has little effect on the process of adjustment of epicyclic motions near the OLR of the bar.